A construction worker accidentally drops a brick from a

Physics: Principles & Problems | 9th Edition | ISBN: 9780078458132 | Authors: Paul W Zitzewitz

Chapter 3: Problem 1 Physics: Principles & Problems 9

A dog runs into a room and sees a cat at the other end of the room. The dog instantly stops running but slides along the wood floor until he stops, by slowing down with a constant acceleration. Sketch a motion diagram for this situation, and use the velocity vectors to find the acceleration vector

Chapter 3: Problem 2 Physics: Principles & Problems 9

Chapter 3: Problem 3 Physics: Principles & Problems 9

Chapter 3: Problem 4 Physics: Principles & Problems 9

Refer to Figure 3-6 to find the average acceleration of the train during the following time intervals. a. 0.0 s to 5.0 s b. 15.0 s to 20.0 s c. 0.0 s to 40.0 s

Chapter 3: Problem 5 Physics: Principles & Problems 9

Plot a v-t graph representing the following motion. An elevator starts at rest from the ground floor of a three-story shopping mall. It accelerates upward for 2.0 s at a rate of 0.5 m/s2, continues up at a constant velocity of 1.0 m/s for 12.0 s, and then experiences a constant downward acceleration of 0.25 m/s2 for 4.0 s as it reaches the third floor

Chapter 3: Problem 6 Physics: Principles & Problems 9

Acceleration Describe the motion of a ball as it rolls up a slanted driveway. The ball starts at 2.50 m/s, slows down for 5.00 s, stops for an instant, and then rolls back down at an increasing speed. The positive direction is chosen to be up the driveway, and the origin is at the place where the motion begins. What is the sign of the balls acceleration as it rolls up the driveway? What is the magnitude of the balls acceleration as it rolls up the driveway?

Chapter 3: Problem 7 Physics: Principles & Problems 9

The race car in the previous problem slows from 36 m/s to 15 m/s over 3.0 s. What is its average acceleration?

Chapter 3: Problem 8 Physics: Principles & Problems 9

A car is coasting backwards downhill at a speed of 3.0 m/s when the driver gets the engine started. After 2.5 s, the car is moving uphill at 4.5 m/s. If uphill is chosen as the positive direction, what is the cars average acceleration?

Chapter 3: Problem 9 Physics: Principles & Problems 9

A bus is moving at 25 m/s when the driver steps on the brakes and brings the bus to a stop in 3.0 s. a. What is the average acceleration of the bus while braking? . If the bus took twice as long to stop, how would the acceleration compare with what you found in part a?

Chapter 3: Problem 10 Physics: Principles & Problems 9

. Rohith has been jogging to the bus stop for 2.0 min at 3.5 m/s when he looks at his watch and sees that he has plenty of time before the bus arrives. Over the next 10.0 s, he slows his pace to a leisurely 0.75 m/s. What was his average acceleration during this 10.0 s?

Chapter 3: Problem 11 Physics: Principles & Problems 9

. If the rate of continental drift were to abruptly slow from 1.0 cm/y to 0.5 cm/y over the time interval of a year, what would be the average acceleration?

Chapter 3: Problem 12 Physics: Principles & Problems 9

Velocity-Time Graph What information can you obtain from a velocity-time graph?

Chapter 3: Problem 13 Physics: Principles & Problems 9

Position-Time and Velocity-Time Graphs Two joggers run at a constant velocity of 7.5 m/s toward the east. At time t ! 0, one is 15 m east of the origin and the other is 15 m west. a. What would be the difference(s) in the positiontime graphs of their motion? b. What would be the difference(s) in their velocitytime graphs?

Chapter 3: Problem 14 Physics: Principles & Problems 9

Velocity Explain how you would use a velocitytime graph to find the time at which an object had a specified velocity

Chapter 3: Problem 15 Physics: Principles & Problems 9

Velocity-Time Graph Sketch a velocity-time graph for a car that goes east at 25 m/s for 100 s, then west at 25 m/s for another 100 s.

Chapter 3: Problem 16 Physics: Principles & Problems 9

Average Velocity and Average Acceleration A canoeist paddles upstream at 2 m/s and then turns around and floats downstream at 4 m/s. The turnaround time is 8 s. a. What is the average velocity of the canoe? b. What is the average acceleration of the canoe?

Chapter 3: Problem 17 Physics: Principles & Problems 9

Critical Thinking A police officer clocked a driver going 32 km/h over the speed limit just as the driver passed a slower car. Both drivers were issued speeding tickets. The judge agreed with the officer that both were guilty. The judgement was issued based on the assumption that the cars must have been going the same speed because they were observed next to each other. Are the judge and the police officer correct? Explain with a sketch, a motion diagram, and a position-time graph.

Chapter 3: Problem 18 Physics: Principles & Problems 9

. A golf ball rolls up a hill toward a miniature-golf hole. Assume that the direction toward the hole is positive. a. If the golf ball starts with a speed of 2.0 m/s and slows at a constant rate of 0.50 m/s2, what is its velocity after 2.0 s? b. What is the golf balls velocity if the constant acceleration continues for 6.0 s? c. Describe the motion of the golf ball in words and with a motion diagram

Chapter 3: Problem 19 Physics: Principles & Problems 9

A bus that is traveling at 30.0 km/h speeds up at a constant rate of 3.5 m/s2. What velocity does it reach 6.8 s later?

Chapter 3: Problem 20 Physics: Principles & Problems 9

If a car accelerates from rest at a constant 5.5 m/s2, how long will it take for the car to reach a velocity of 28 m/s?

Chapter 3: Problem 21 Physics: Principles & Problems 9

A car slows from 22 m/s to 3.0 m/s at a constant rate of 2.1 m/s2. How many seconds are required before the car is traveling at 3.0 m/s?

Chapter 3: Problem 22 Physics: Principles & Problems 9

Chapter 3: Problem 23 Physics: Principles & Problems 9

Use dimensional analysis to convert an airplanes speed of 75 m/s to km/h

Chapter 3: Problem 24 Physics: Principles & Problems 9

Chapter 3: Problem 25 Physics: Principles & Problems 9

A car is driven at a constant velocity of 25 m/s for 10.0 min. The car runs out of gas and the driver walks in the same direction at 1.5 m/s for 20.0 min to the nearest gas station. The driver takes 2.0 min to fill a gasoline can, then walks back to the car at 1.2 m/s and eventually drives home at 25 m/s in the direction opposite that of the original trip. a. Draw a v-t graph using seconds as your time unit. Calculate the distance the driver walked to the gas station to find the time it took him to walk back to the car. Draw a position-time graph for the situation using the areas under the velocity-time graph.

Chapter 3: Problem 26 Physics: Principles & Problems 9

A skateboarder is moving at a constant velocity of 1.75 m/s when she starts up an incline that causes her to slow down with a constant acceleration of !0.20 m/s2. How much time passes from when she begins to slow down until she begins to move back down the incline?

Chapter 3: Problem 27 Physics: Principles & Problems 9

A race car travels on a racetrack at 44 m/s and slows at a constant rate to a velocity of 22 m/s over 11 s. How far does it move during this time?

Chapter 3: Problem 28 Physics: Principles & Problems 9

. A car accelerates at a constant rate from 15 m/s to 25 m/s while it travels a distance of 125 m. How long does it take to achieve this speed?

Chapter 3: Problem 29 Physics: Principles & Problems 9

A bike rider pedals with constant acceleration to reach a velocity of 7.5 m/s over a time of 4.5 s. During the period of acceleration, the bikes displacement is 19 m. What was the initial velocity of the bike?

Chapter 3: Problem 30 Physics: Principles & Problems 9

A man runs at a velocity of 4.5 m/s for 15.0 min. When going up an increasingly steep hill, he slows down at a constant rate of 0.05 m/s2 for 90.0 s and comes to a stop. How far did he run?

Chapter 3: Problem 31 Physics: Principles & Problems 9

. Sekazi is learning to ride a bike without training wheels. His father pushes him with a constant acceleration of 0.50 m/s2 for 6.0 s, and then Sekazi continues at 3.0 m/s for another 6.0 s before falling. What is Sekazis displacement? Solve this problem by constructing a velocity-time graph for Sekazis motion and computing the area underneath the graphed line

Chapter 3: Problem 32 Physics: Principles & Problems 9

You start your bicycle ride at the top of a hill. You coast down the hill at a constant acceleration of 2.00 m/s2. When you get to the bottom of the hill, you are moving at 18.0 m/s, and you pedal to maintain that speed. If you continue at this speed for 1.00 min, how far will you have gone from the time you left the hilltop?

Chapter 3: Problem 33 Physics: Principles & Problems 9

Sunee is training for an upcoming 5.0-km race. She starts out her training run by moving at a constant pace of 4.3 m/s for 19 min. Then she accelerates at a constant rate until she crosses the finish line, 19.4 s later. What is her acceleration during the last portion of the training run?

Chapter 3: Problem 34 Physics: Principles & Problems 9

Acceleration A woman driving at a speed of 23 m/s sees a deer on the road ahead and applies the brakes when she is 210 m from the deer. If the deer does not move and the car stops right before it hits the deer, what is the acceleration provided by the cars brakes?

Chapter 3: Problem 35 Physics: Principles & Problems 9

Displacement If you were given initial and final velocities and the constant acceleration of an object, and you were asked to find the displacement, what equation would you use?

Chapter 3: Problem 36 Physics: Principles & Problems 9

Distance An in-line skater first accelerates from 0.0 m/s to 5.0 m/s in 4.5 s, then continues at this constant speed for another 4.5 s. What is the total distance traveled by the in-line skater?

Chapter 3: Problem 37 Physics: Principles & Problems 9

Final Velocity A plane travels a distance of 5.0!102 m while being accelerated uniformly from rest at the rate of 5.0 m/s2. What final velocity does it attain?

Chapter 3: Problem 38 Physics: Principles & Problems 9

Final Velocity An airplane accelerated uniformly from rest at the rate of 5.0 m/s2 for 14 s. What final velocity did it attain?

Chapter 3: Problem 39 Physics: Principles & Problems 9

. Distance An airplane starts from rest and accelerates at a constant 3.00 m/s2 for 30.0 s before leaving the ground. a. How far did it move? b. How fast was the airplane going when it took

Chapter 3: Problem 40 Physics: Principles & Problems 9

Graphs A sprinter walks up to the starting blocks at a constant speed and positions herself for the start of the race. She waits until she hears the starting pistol go off, and then accelerates rapidly until she attains a constant velocity. She maintains this velocity until she crosses the finish line, and then she slows down to a walk, taking more time to slow down than she did to speed up at the beginning of the race. Sketch a velocity-time and a position-time graph to represent her motion. Draw them one above the other on the same time scale. Indicate on your p-t graph where the starting blocks and finish line are.

Chapter 3: Problem 41 Physics: Principles & Problems 9

Critical Thinking Describe how you could calculate the acceleration of an automobile. Specify the measuring instruments and the procedures that you would use.

Chapter 3: Problem 42 Physics: Principles & Problems 9

A construction worker accidentally drops a brick from a high scaffold. a. What is the velocity of the brick after 4.0 s? b. How far does the brick fall during this time?

Chapter 3: Problem 43 Physics: Principles & Problems 9

Suppose for the previous problem you choose your coordinate system so that the opposite direction is positive. a. What is the bricks velocity after 4.0 s? b. How far does the brick fall during this time?

Chapter 3: Problem 44 Physics: Principles & Problems 9

. A student drops a ball from a window 3.5 m above the sidewalk. How fast is it moving when it hits the sidewalk?

Chapter 3: Problem 45 Physics: Principles & Problems 9

A tennis ball is thrown straight up with an initial speed of 22.5 m/s. It is caught at the same distance above the ground. a. How high does the ball rise? b. How long does the ball remain in the air? Hint: The time it takes the ball to rise equals the time it takes to fall.

Chapter 3: Problem 46 Physics: Principles & Problems 9

You decide to flip a coin to determine whether to do your physics or English homework first. The coin is flipped straight up. a. If the coin reaches a high point of 0.25 m above where you released it, what was its initial speed? b. If you catch it at the same height as you released it, how much time did it spend in the air?

Chapter 3: Problem 47 Physics: Principles & Problems 9

Maximum Height and Flight Time Acceleration due to gravity on Mars is about one-third that on Earth. Suppose you throw a ball upward with the same velocity on Mars as on Earth. a. How would the balls maximum height compare to that on Earth? b. How would its flight time compare?

Chapter 3: Problem 48 Physics: Principles & Problems 9

Velocity and Acceleration Suppose you throw a ball straight up into the air. Describe the changes in the velocity of the ball. Describe the changes in the acceleration of the ball.

Chapter 3: Problem 49 Physics: Principles & Problems 9

Final Velocity Your sister drops your house keys down to you from the second floor window. If you catch them 4.3 m from where your sister dropped them, what is the velocity of the keys when you catch them?

Chapter 3: Problem 50 Physics: Principles & Problems 9

Initial Velocity A student trying out for the football team kicks the football straight up in the air. The ball hits him on the way back down. If it took 3.0 s from the time when the student punted the ball until he gets hit by the ball, what was the footballs initial velocity?

Chapter 3: Problem 51 Physics: Principles & Problems 9

Maximum Height When the student in the previous problem kicked the football, approximately how high did the football travel?

Chapter 3: Problem 52 Physics: Principles & Problems 9

When a ball is thrown vertically upward, it continues upward until it reaches a certain position, and then it falls downward. At that highest point, its velocity is instantaneously zero. Is the ball accelerating at the highest point? Devise an experiment to prove or disprove your answer.

Chapter 3: Problem 53 Physics: Principles & Problems 9

Chapter 3: Problem 54 Physics: Principles & Problems 9

. How are velocity and acceleration related? (3.1)

Chapter 3: Problem 55 Physics: Principles & Problems 9

. Give an example of each of the following. (3.1) a. an object that is slowing down, but has a positive acceleration b. an object that is speeding up, but has a negative acceleration

Chapter 3: Problem 56 Physics: Principles & Problems 9

Chapter 3: Problem 57 Physics: Principles & Problems 9

What does the slope of the tangent to the curve on a velocity-time graph measure? (3.1)

Chapter 3: Problem 58 Physics: Principles & Problems 9

Can a car traveling on an interstate highway have a negative velocity and a positive acceleration at the same time? Explain. Can the cars velocity change signs while it is traveling with constant acceleration? Explain.

Chapter 3: Problem 59 Physics: Principles & Problems 9

Can the velocity of an object change when its acceleration is constant? If so, give an example. If not, explain.

Chapter 3: Problem 60 Physics: Principles & Problems 9

If an objects velocity-time graph is a straight line parallel to the t-axis, what can you conclude about the objects acceleration?

Chapter 3: Problem 61 Physics: Principles & Problems 9

What quantity is represented by the area under a velocity-time graph?

Chapter 3: Problem 62 Physics: Principles & Problems 9

Write a summary of the equations for position, velocity, and time for an object experiencing motion with uniform acceleration.

Chapter 3: Problem 63 Physics: Principles & Problems 9

Explain why an aluminum ball and a steel ball of similar size and shape, dropped from the same height, reach the ground at the same time

Chapter 3: Problem 64 Physics: Principles & Problems 9

Give some examples of falling objects for which air resistance cannot be ignored

Chapter 3: Problem 65 Physics: Principles & Problems 9

Give some examples of falling objects for which air resistance can be ignored.

Chapter 3: Problem 66 Physics: Principles & Problems 9

Does a car that is slowing down always have a negative acceleration? Explain.

Chapter 3: Problem 67 Physics: Principles & Problems 9

Croquet A croquet ball, after being hit by a mallet, slows down and stops. Do the velocity and acceleration of the ball have the same signs?

Chapter 3: Problem 68 Physics: Principles & Problems 9

If an object has zero acceleration, does it mean its velocity is zero? Give an example

Chapter 3: Problem 69 Physics: Principles & Problems 9

If an object has zero velocity at some instant, is its acceleration zero? Give an example.

Chapter 3: Problem 70 Physics: Principles & Problems 9

. If you were given a table of velocities of an object at various times, how would you find out whether the acceleration was constant?

Chapter 3: Problem 71 Physics: Principles & Problems 9

The three notches in the graph in Figure 3-16 occur where the driver changed gears. Describe the changes in velocity and acceleration of the car while in first gear. Is the acceleration just before a gear change larger or smaller than the acceleration just after the change? Explain your answer

Chapter 3: Problem 72 Physics: Principles & Problems 9

Use the graph in Figure 3-16 and determine the time interval during which the acceleration is largest and the time interval during which the acceleration is smallest.

Chapter 3: Problem 73 Physics: Principles & Problems 9

Chapter 3: Problem 74 Physics: Principles & Problems 9

Chapter 3: Problem 75 Physics: Principles & Problems 9

An object shot straight up rises for 7.0 s before it reaches its maximum height. A second object falling from rest takes 7.0 s to reach the ground. Compare the displacements of the two objects during this time interval

Chapter 3: Problem 76 Physics: Principles & Problems 9

The Moon The value of g on the Moon is one-sixth of its value on Earth. a. Would a ball that is dropped by an astronaut hit the surface of the Moon with a greater, equal, or lesser speed than that of a ball dropped from the same height to Earth? b. Would it take the ball more, less, or equal time to fall?

Chapter 3: Problem 77 Physics: Principles & Problems 9

Jupiter The planet Jupiter has about three times the gravitational acceleration of Earth. Suppose a ball is thrown vertically upward with the same initial velocity on Earth and on Jupiter. Neglect the effects of Jupiters atmospheric resistance and assume that gravity is the only force on the ball. a. How does the maximum height reached by the ball on Jupiter compare to the maximum height reached on Earth? b. If the ball on Jupiter were thrown with an initial velocity that is three times greater, how would this affect your answer to part a?

Chapter 3: Problem 78 Physics: Principles & Problems 9

Rock A is dropped from a cliff and rock B is thrown upward from the same position. a. When they reach the ground at the bottom of the cliff, which rock has a greater velocity? . Which has a greater acceleration? Which arrives first?

Chapter 3: Problem 79 Physics: Principles & Problems 9

. A car is driven for 2.0 h at 40.0 km/h, then for another 2.0 h at 60.0 km/h in the same direction. a. What is the cars average velocity? . What is the cars average velocity if it is driven 1.0!102 km at each of the two speeds?

Chapter 3: Problem 80 Physics: Principles & Problems 9

Find the uniform acceleration that causes a cars velocity to change from 32 m/s to 96 m/s in an 8.0-s period

Chapter 3: Problem 81 Physics: Principles & Problems 9

A car with a velocity of 22 m/s is accelerated uniformly at the rate of 1.6 m/s2 for 6.8 s. What is its final velocity?

Chapter 3: Problem 82 Physics: Principles & Problems 9

Chapter 3: Problem 83 Physics: Principles & Problems 9

Chapter 3: Problem 84 Physics: Principles & Problems 9

Determine the final velocity of a proton that has an initial velocity of 2.35!105 m/s and then is accelerated uniformly in an electric field at the rate of "1.10!1012 m/s2 for 1.50!10"7 s.

Chapter 3: Problem 85 Physics: Principles & Problems 9

Sports Cars Marco is looking for a used sports car. He wants to buy the one with the greatest acceleration. Car A can go from 0 m/s to 17.9 m/s in 4.0 s; car B can accelerate from 0 m/s to 22.4 m/s in 3.5 s; and car C can go from 0 to 26.8 m/s in 6.0 s. Rank the three cars from greatest acceleration to least, specifically indicating any ties.

Chapter 3: Problem 86 Physics: Principles & Problems 9

Supersonic Jet A supersonic jet flying at 145 m/s experiences uniform acceleration at the rate of 23.1 m/s2 for 20.0 s. a. What is its final velocity? b. The speed of sound in air is 331 m/s. What is the planes speed in terms of the speed of sound?

Chapter 3: Problem 87 Physics: Principles & Problems 9

Refer to Figure 3-19 to find the distance traveled during the following time intervals. a. t # 0.0 s and t # 5.0 s b. t # 5.0 s and t # 10.0 s c. t # 10.0 s and t # 15.0 s d. t # 0.0 s and t # 25.0 s

Chapter 3: Problem 88 Physics: Principles & Problems 9

A dragster starting from rest accelerates at 49 m/s2. How fast is it going when it has traveled 325 m?

Chapter 3: Problem 89 Physics: Principles & Problems 9

A car moves at 12 m/s and coasts up a hill with a uniform acceleration of "1.6 m/s2. a. What is its displacement after 6.0 s? b. What is its displacement after 9.0 s?

Chapter 3: Problem 90 Physics: Principles & Problems 9

Race Car A race car can be slowed with a constant acceleration of "11 m/s2. a. If the car is going 55 m/s, how many meters will it travel before it stops? b. How many meters will it take to stop a car going twice as fast?

Chapter 3: Problem 91 Physics: Principles & Problems 9

A car is traveling 20.0 m/s when the driver sees a child standing on the road. She takes 0.80 s to react, then steps on the brakes and slows at 7.0 m/s2. How far does the car go before it stops?

Chapter 3: Problem 92 Physics: Principles & Problems 9

Airplane Determine the displacement of a plane that experiences uniform acceleration from 66 m/s to 88 m/s in 12 s.

Chapter 3: Problem 93 Physics: Principles & Problems 9

. How far does a plane fly in 15 s while its velocity is changing from 145 m/s to 75 m/s at a uniform rate of acceleration?

Chapter 3: Problem 94 Physics: Principles & Problems 9

Police Car A speeding car is traveling at a constant speed of 30.0 m/s when it passes a stopped police car. The police car accelerates at 7.0 m/s2. How fast will it be going when it catches up with the speeding car?

Chapter 3: Problem 95 Physics: Principles & Problems 9

Road Barrier The driver of a car going 90.0 km/h suddenly sees the lights of a barrier 40.0 m ahead. It takes the driver 0.75 s to apply the brakes, and the average acceleration during braking is "10.0 m/s2. a. Determine whether the car hits the barrier. b. What is the maximum speed at which the car could be moving and not hit the barrier 40.0 m ahead? Assume that the acceleration doesnt change.

Chapter 3: Problem 96 Physics: Principles & Problems 9

A student drops a penny from the top of a tower and decides that she will establish a coordinate system in which the direction of the pennys motion is positive. What is the sign of the acceleration of the penny?

Chapter 3: Problem 97 Physics: Principles & Problems 9

Suppose an astronaut drops a feather from 1.2 m above the surface of the Moon. If the acceleration due to gravity on the Moon is 1.62 m/s2 downward, how long does it take the feather to hit the Moons surface?

Chapter 3: Problem 98 Physics: Principles & Problems 9

A stone that starts at rest is in free fall for 8.0 s. a. Calculate the stones velocity after 8.0 s. b. What is the stones displacement during this time?

Chapter 3: Problem 99 Physics: Principles & Problems 9

A bag is dropped from a hovering helicopter. The bag has fallen for 2.0 s. What is the bags velocity? How far has the bag fallen?

Chapter 3: Problem 100 Physics: Principles & Problems 9

You throw a ball downward from a window at a speed of 2.0 m/s. How fast will it be moving when it hits the sidewalk 2.5 m below?

Chapter 3: Problem 101 Physics: Principles & Problems 9

If you throw the ball in the previous problem up instead of down, how fast will it be moving when it hits the sidewalk?

Chapter 3: Problem 102 Physics: Principles & Problems 9

. Beanbag You throw a beanbag in the air and catch it 2.2 s later. a. How high did it go? b. What was its initial velocity?

Chapter 3: Problem 103 Physics: Principles & Problems 9

A spaceship far from any star or planet experiences uniform acceleration from 65.0 m/s to 162.0 m/s in 10.0 s. How far does it move?

Chapter 3: Problem 104 Physics: Principles & Problems 9

Chapter 3: Problem 105 Physics: Principles & Problems 9

Bicycle A bicycle accelerates from 0.0 m/s to 4.0 m/s in 4.0 s. What distance does it travel?

Chapter 3: Problem 106 Physics: Principles & Problems 9

A weather balloon is floating at a constant height above Earth when it releases a pack of instruments. a. If the pack hits the ground with a velocity of !73.5 m/s, how far did the pack fall? b. How long did it take for the pack to fall?

Chapter 3: Problem 107 Physics: Principles & Problems 9

Baseball A baseball pitcher throws a fastball at a speed of 44 m/s. The acceleration occurs as the pitcher holds the ball in his hand and moves it through an almost straight-line distance of 3.5 m. Calculate the acceleration, assuming that it is constant and uniform. Compare this acceleration to the acceleration due to gravity

Chapter 3: Problem 108 Physics: Principles & Problems 9

Chapter 3: Problem 109 Physics: Principles & Problems 9

. Engineers are developing new types of guns that might someday be used to launch satellites as if they were bullets. One such gun can give a small object a velocity of 3.5 km/s while moving it through a distance of only 2.0 cm. a. What acceleration does the gun give this object? b. Over what time interval does the acceleration take place?

Chapter 3: Problem 110 Physics: Principles & Problems 9

Sleds Rocket-powered sleds are used to test the responses of humans to acceleration. Starting from rest, one sled can reach a speed of 444 m/s in 1.80 s and can be brought to a stop again in 2.15 s. a. Calculate the acceleration of the sled when starting, and compare it to the magnitude of the acceleration due to gravity, 9.80 m/s2. b. Find the acceleration of the sled as it is braking and compare it to the magnitude of the acceleration due to gravity.

Chapter 3: Problem 111 Physics: Principles & Problems 9

Chapter 3: Problem 112 Physics: Principles & Problems 9

A truck is stopped at a stoplight. When the light turns green, the truck accelerates at 2.5 m/s2. At the same instant, a car passes the truck going 15 m/s. Where and when does the truck catch up with the car?

Chapter 3: Problem 113 Physics: Principles & Problems 9

Chapter 3: Problem 114 Physics: Principles & Problems 9

Chapter 3: Problem 115 Physics: Principles & Problems 9

Cargo A helicopter is rising at 5.0 m/s when a bag of its cargo is dropped. The bag falls for 2.0 s. a. What is the bags velocity? b. How far has the bag fallen? c. How far below the helicopter is the bag?

Chapter 3: Problem 116 Physics: Principles & Problems 9

Apply CBLs Design a lab to measure the distance an accelerated object moves over time. Use equal time intervals so that you can plot velocity over time as well as distance. A pulley at the edge of a table with a mass attached is a good way to achieve uniform acceleration. Suggested materials include a motion detector, CBL, lab cart, string, pulley, C-clamp, and masses. Generate distancetime and velocity-time graphs using different masses on the pulley. How does the change in mass affect your graphs?

Chapter 3: Problem 117 Physics: Principles & Problems 9

Analyze and Conclude Which has the greater acceleration: a car that increases its speed from 50 km/h to 60 km/h, or a bike that goes from 0 km/h to 10 km/h in the same time? Explain

Chapter 3: Problem 118 Physics: Principles & Problems 9

. Analyze and Conclude An express train, traveling at 36.0 m/s, is accidentally sidetracked onto a local train track. The express engineer spots a local train exactly 1.00"102 m ahead on the same track and traveling in the same direction. The local engineer is unaware of the situation. The express engineer jams on the brakes and slows the express train at a constant rate of 3.00 m/s2. If the speed of the local train is 11.0 m/s, will the express train be able to stop in time, or will there be a collision? To solve this problem, take the position of the express train when the engineer first sights the local train as a point of origin. Next, keeping in mind that the local train has exactly a 1.00"102 m lead, calculate how far each train is from the origin at the end of the 12.0 s it would take the express train to stop (accelerate at #3.00 m/s2 from 36 m/s to 0 m/s). a. On the basis of your calculations, would you conclude that a collision will occur? b. The calculations that you made do not allow for the possibility that a collision might take place before the end of the 12 s required for the express train to come to a halt. To check this, take the position of the express train when the engineer first sights the local train as the point of origin and calculate the position of each train at the end of each second after the sighting. Make a table showing the distance of each train from the origin at the end of each second. Plot these positions on the same graph and draw two lines. Use your graph to check your answer to part a.

Chapter 3: Problem 119 Physics: Principles & Problems 9

Research and describe Galileos contributions to physics

Chapter 3: Problem 120 Physics: Principles & Problems 9

Research the maximum acceleration a human body can withstand without blacking out. Discuss how this impacts the design of three common entertainment or transportation devices.

Chapter 3: Problem 121 Physics: Principles & Problems 9

Solve the following problems. Express your answers in scientific notation. (Chapter 1) a. 6.2"10#4 m $ 5.7"10#3 m b. 8.7"108 km # 3.4"107 m c. (9.21"10#5 cm)(1.83"108 cm) d. (2.63"10#6 m)/(4.08"106 s)

Chapter 3: Problem 122 Physics: Principles & Problems 9

The equation below describes the motion of an object. Create the corresponding position-time graph and motion diagram. Then write a physics problem that could be solved using that equation. Be creative. d ! (35.0 m/s) t # 5.0 m (Chapter 2)

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