Answer: An ice sled powered by a rocket engine starts from

Chapter 2: Problem 1 Holt Physics: Student Edition 2009 1

On the graph below, what is the total distance traveled during the recorded time interval? What is the displacement?

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Chapter 2: Problem 2 Holt Physics: Student Edition 2009 1

On a position-time graph such as the one above, what represents the instantaneous velocity?

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Chapter 2: Problem 3 Holt Physics: Student Edition 2009 1

The position-time graph for a bug crawling along a line is shown in item 4 below. Determine whether the velocity is positive, negative, or zero at each of the times marked on the graph.

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Chapter 2: Problem 4 Holt Physics: Student Edition 2009 1

Use the position-time graph below to answer the following questions: a. During which time interval(s) is the velocity negative? b. During which time interval(s) is the velocity positive?

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Chapter 2: Problem 5 Holt Physics: Student Edition 2009 1

If the average velocity of a duck is zero in a given time interval, what can you say about the displacement of the duck for that interval?

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Chapter 2: Problem 6 Holt Physics: Student Edition 2009 1

Velocity can be either positive or negative, depending on the direction of the displacement. The time interval, _t, is always positive.Why?

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Chapter 2: Problem 7 Holt Physics: Student Edition 2009 1

A school bus takes 0.530 h to reach the school from your house. If the average velocity of the bus is 19.0 km/h to the east, what is the displacement?

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Chapter 2: Problem 8 Holt Physics: Student Edition 2009 1

The Olympic record for the marathon is 2.00 h, 9.00 min, 21.0 s. If the average speed of a runner achieving this record is 5.436 m/s, what is the marathon distance?

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Chapter 2: Problem 9 Holt Physics: Student Edition 2009 1

Two cars are traveling on a desert road, as shown below. After 5.0 s, they are side by side at the next telephone pole. The distance between the poles is 70.0 m. Identify the following quantities: a. the displacement of car A after 5.0 s b. the displacement of car B after 5.0 s c. the average velocity of car A during 5.0 s d. the average velocity of car B during 5.0 s 1

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Chapter 2: Problem 10 Holt Physics: Student Edition 2009 1

Sally travels by car from one city to another. She drives for 30.0 min at 80.0 km/h, 12.0 min at 105 km/h, and 45.0 min at 40.0 km/h, and she spends 15.0 min eating lunch and buying gas. a. Determine the average speed for the trip. b. Determine the total distance traveled. 1

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Chapter 2: Problem 11 Holt Physics: Student Edition 2009 1

Runner A is initially 6.0 km west of a flagpole and is running with a constant velocity of 9.0 km/h due east. Runner B is initially 5.0 km east of the flagpole and is running with a constant velocity of 8.0 km/h due west.What will be the distance of the two runners from the flagpole when their paths cross? (It is not necessary to convert your answer from kilometers to meters for this problem. You may leave it in kilometers.) 1

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Chapter 2: Problem 12 Holt Physics: Student Edition 2009 1

What would be the acceleration of a turtle that is moving with a constant velocity of 0.25 m/s to the right? 1

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Chapter 2: Problem 13 Holt Physics: Student Edition 2009 1

Sketch the velocity-time graphs for the following motions. a. a city bus that is moving with a constant velocity b. a wheelbarrow that is speeding up at a uniform rate of acceleration while moving in the positive direction c. a tiger that is speeding up at a uniform rate of acceleration while moving in the negative direction d. an iguana that is slowing down at a uniform rate of acceleration while moving in the positive direction e. a camel that is slowing down at a uniform rate of acceleration while moving in the negative direction 1

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Chapter 2: Problem 14 Holt Physics: Student Edition 2009 1

If a car is traveling eastward, can its acceleration be westward? Explain your answer, and use an example in your explanation. 1

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Chapter 2: Problem 15 Holt Physics: Student Edition 2009 1

The strobe photographs below show a disk moving from left to right under different conditions. The time interval between images is constant. Assuming that the direction to the right is positive, identify the following types of motion in each photograph. (Some may have more than one type of motion.) a. the acceleration is positive b. the acceleration is negative c. the velocity is constant 1

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Chapter 2: Problem 16 Holt Physics: Student Edition 2009 1

A car traveling in a straight line has a velocity of +5.0 m/s. After an acceleration of 0.75 m/s2, the cars velocity is +8.0 m/s. In what time interval did the acceleration occur? 1

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Chapter 2: Problem 17 Holt Physics: Student Edition 2009 1

The velocity-time graph for an object moving along a straight path is shown below. Find the average accelerations during the time intervals 0.0 s to 5.0 s, 5.0 s to 15.0 s, and 0.0 s to 20.0 s. 1

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Chapter 2: Problem 18 Holt Physics: Student Edition 2009 1

A bus slows down uniformly from 75.0 km/h (21 m/s) to 0 km/h in 21 s. How far does it travel before stopping? 1

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Chapter 2: Problem 19 Holt Physics: Student Edition 2009 1

A car accelerates uniformly from rest to a speed of 65 km/h (18 m/s) in 12 s. Find the distance the car travels during this time. 2

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Chapter 2: Problem 20 Holt Physics: Student Edition 2009 1

A car traveling at +7.0 m/s accelerates at the rate of +0.80 m/s2 for an interval of 2.0 s. Find vf . 2

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Chapter 2: Problem 21 Holt Physics: Student Edition 2009 1

A car accelerates from rest at 3.00 m/s2. a. What is the velocity at the end of 5.0 s? b. What is the displacement after 5.0 s? 2

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Chapter 2: Problem 22 Holt Physics: Student Edition 2009 1

A car starts from rest and travels for 5.0 s with a uniform acceleration of +1.5 m/s2. The driver then applies the brakes, causing a uniform acceleration of 2.0 m/s2. If the brakes are applied for 3.0 s, how fast is the car going at the end of the braking period, and how far has it gone from its start? 2

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Chapter 2: Problem 23 Holt Physics: Student Edition 2009 1

A boy sledding down a hill accelerates at 1.40 m/s2. If he started from rest, in what distance would he reach a speed of 7.00 m/s? 2

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Chapter 2: Problem 24 Holt Physics: Student Edition 2009 1

A sailboat starts from rest and accelerates at a rate of 0.21 m/s2 over a distance of 280 m. a. Find the magnitude of the boats final velocity. b. Find the time it takes the boat to travel this distance. 2

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Chapter 2: Problem 25 Holt Physics: Student Edition 2009 1

An elevator is moving upward at 1.20 m/s when it experiences an acceleration of 0.31 m/s2 downward, over a distance of 0.75 m.What will its final velocity be? 2

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Chapter 2: Problem 26 Holt Physics: Student Edition 2009 1

A ball is thrown vertically upward. a. What happens to the balls velocity while the ball is in the air? b. What is its velocity when it reaches its maximum altitude? c. What is its acceleration when it reaches its maximum altitude? d. What is its acceleration just before it hits the ground? e. Does its acceleration increase, decrease, or remain constant? 2

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Chapter 2: Problem 27 Holt Physics: Student Edition 2009 1

The image at right is a strobe photograph of two falling balls released simultaneously. (This motion does not take place in a vacuum.) The ball on the left side is solid, and the ball on the right side is a hollow table-tennis ball. Analyze the motion of both balls in terms of velocity and acceleration. 2

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Chapter 2: Problem 28 Holt Physics: Student Edition 2009 1

A juggler throws a bowling pin into the air with an initial velocity vi. Another juggler drops a pin at the same instant. Compare the accelerations of the two pins while they are in the air. 2

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Chapter 2: Problem 29 Holt Physics: Student Edition 2009 1

A bouquet is thrown upward. a. Will the value for the bouquets displacement be the same no matter where you place the origin of the coordinate system? b. Will the value for the bouquets velocity be the same? c. Will the value for the bouquets acceleration be the same? 3

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Chapter 2: Problem 30 Holt Physics: Student Edition 2009 1

A worker drops a wrench from the top of a tower 80.0 m tall. What is the velocity when the wrench strikes the ground? 3

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Chapter 2: Problem 31 Holt Physics: Student Edition 2009 1

A peregrine falcon dives at a pigeon. The falcon starts downward from rest with free-fall acceleration. If the pigeon is 76.0 m below the initial position of the falcon, how long does the falcon take to reach the pigeon? Assume that the pigeon remains at rest. 3

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Chapter 2: Problem 32 Holt Physics: Student Edition 2009 1

A ball is thrown upward from the ground with an initial speed of 25 m/s; at the same instant, a ball is dropped from rest from a building 15 m high. After how long will the balls be at the same height? 3

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Chapter 2: Problem 33 Holt Physics: Student Edition 2009 1

If the average speed of an orbiting space shuttle is 27 800 km/h, determine the time required for it to circle Earth. Assume that the shuttle is orbiting about 320.0 km above Earths surface, and that Earths radius is 6380 km. 3

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Chapter 2: Problem 34 Holt Physics: Student Edition 2009 1

A ball is thrown directly upward into the air. The graph below shows the vertical position of the ball with respect to time. a. How much time does the ball take to reach its maximum height? b. How much time does the ball take to reach one-half its maximum height? c. Estimate the slope of y/t at t = 0.05 s, t = 0.10 s, t = 0.15 s, and t = 0.20 s. On your paper, draw a coordinate system with velocity (v) on the y-axis and time (t) on the x-axis. Plot your velocity estimates against time. d. From your graph, determine what the acceleration on the ball is. 3

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Chapter 2: Problem 35 Holt Physics: Student Edition 2009 1

A train travels between stations 1 and 2, as shown below. The engineer of the train is instructed to start from rest at station 1 and accelerate uniformly between points A and B, then coast with a uniform velocity between points B and C, and finally accelerate uniformly between points C and D until the train stops at station 2. The distances AB, BC, and CD are all equal, and it takes 5.00 min to travel between the two stations. Assume that the uniform accelerations have the same magnitude, even when they are opposite in direction. b. How much of this 5.00 min period does the train spend between points B and C? c. How much of this 5.00 min period does the train spend between points C and D? 3

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Chapter 2: Problem 36 Holt Physics: Student Edition 2009 1

Two students are on a balcony 19.6 m above the street. One student throws a ball vertically downward at 14.7 m/s. At the same instant, the other student throws a ball vertically upward at the same speed. The second ball just misses the balcony on the way down. a. What is the difference in the time the balls spend in the air? b. What is the velocity of each ball as it strikes the ground? c. How far apart are the balls 0.800 s after they are thrown? 3

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Chapter 2: Problem 37 Holt Physics: Student Edition 2009 1

A rocket moves upward, starting from rest with an acceleration of +29.4 m/s2 for 3.98 s. It runs out of fuel at the end of the 3.98 s but does not stop. How high does it rise above the ground? 3

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Chapter 2: Problem 38 Holt Physics: Student Edition 2009 1

Two cars travel westward along a straight highway, one at a constant velocity of 85 km/h, and the other at a constant velocity of 115 km/h. a. Assuming that both cars start at the same point, how much sooner does the faster car arrive at a destination 16 km away? b. How far must the cars travel for the faster car to arrive 15 min before the slower car? 3

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Chapter 2: Problem 39 Holt Physics: Student Edition 2009 1

A small first-aid kit is dropped by a rock climber who is descending steadily at 1.3 m/s. After 2.5 s, what is the velocity of the first-aid kit, and how far is the kit below the climber? 4

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Chapter 2: Problem 40 Holt Physics: Student Edition 2009 1

A small fish is dropped by a pelican that is rising steadily at 0.50 m/s. a. After 2.5 s, what is the velocity of the fish? b. How far below the pelican is the fish after 2.5 s? 4

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Chapter 2: Problem 41 Holt Physics: Student Edition 2009 1

A ranger in a national park is driving at 56 km/h when a deer jumps onto the road 65 m ahead of the vehicle. After a reaction time of t s, the ranger applies the brakes to produce an acceleration of 3.0 m/s2. What is the maximum reaction time allowed if the ranger is to avoid hitting the deer? 4

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Chapter 2: Problem 42 Holt Physics: Student Edition 2009 1

A speeder passes a parked police car at 30.0 m/s. The police car starts from rest with a uniform acceleration of 2.44 m/s2. a. How much time passes before the speeder is overtaken by the police car? b. How far does the speeder get before being overtaken by the police car? 4

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Chapter 2: Problem 43 Holt Physics: Student Edition 2009 1

An ice sled powered by a rocket engine starts from rest on a large frozen lake and accelerates at +13.0 m/s2. At t1 the rocket engine is shut down and the sled moves with constant velocity v until t2. The total distance traveled by the sled is 5.30 103 m and the total time is 90.0 s. Find t1, t2, and v. (See Appendix A for hints on solving quadratic equations.) 4

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Chapter 2: Problem 44 Holt Physics: Student Edition 2009 1

At the 5800 m mark, the sled in the previous question begins to accelerate at 7.0 m/s2. Use your answers from item 43 to answer the following questions. a. What is the final position of the sled when it comes to rest? b. How long does it take for the sled to come to rest? 4

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Chapter 2: Problem 45 Holt Physics: Student Edition 2009 1

A tennis ball with a velocity of +10.0 m/s to the right is thrown perpendicularly at a wall. After striking the wall, the ball rebounds in the opposite direction with a velocity of 8.0 m/s to the left. If the ball is in contact with the wall for 0.012 s, what is the average acceleration of the ball while it is in contact with the wall? 4

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Chapter 2: Problem 46 Holt Physics: Student Edition 2009 1

A parachutist descending at a speed of 10.0 m/s loses a shoe at an altitude of 50.0 m. a. When does the shoe reach the ground? b. What is the velocity of the shoe just before it hits the ground? 4

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Chapter 2: Problem 47 Holt Physics: Student Edition 2009 1

A mountain climber stands at the top of a 50.0 m cliff hanging over a calm pool of water. The climber throws two stones vertically 1.0 s apart and observes that they cause a single splash when they hit the water. The first stone has an initial velocity of +2.0 m/s. a. How long after release of the first stone will the two stones hit the water? b. What is the initial velocity of the second stone when it is thrown? c. What will the velocity of each stone be at the instant both stones hit the water? 4

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Chapter 2: Problem 48 Holt Physics: Student Edition 2009 1

A model rocket is launched straight upward with an initial speed of 50.0 m/s. It accelerates with a constant upward acceleration of 2.00 m/s2 until its engines stop at an altitude of 150 m. a. What is the maximum height reached by the rocket? b. When does the rocket reach maximum height? c. How long is the rocket in the air? 4

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Chapter 2: Problem 49 Holt Physics: Student Edition 2009 1

A professional race-car driver buys a car that can accelerate at +5.9 m/s2. The racer decides to race against another driver in a souped-up stock car. Both start from rest, but the stock-car driver leaves 1.0 s before the driver of the race car. The stock car moves with a constant acceleration of +3.6 m/s2. a. Find the time it takes the race-car driver to overtake the stock-car driver. b. Find the distance the two drivers travel before they are side by side. c. Find the velocities of both cars at the instant they are side by side. 5

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Chapter 2: Problem 50 Holt Physics: Student Edition 2009 1

Two cars are traveling along a straight line in the same direction, the lead car at 25 m/s and the other car at 35 m/s. At the moment the cars are 45 m apart, the lead driver applies the brakes, causing the car to have an acceleration of 2.0 m/s2. a. How long does it take for the lead car to stop? b. Assume that the driver of the chasing car applies the brakes at the same time as the driver of the lead car. What must the chasing cars minimum negative acceleration be to avoid hitting the lead car? c. How long does it take the chasing car to stop? 5

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Chapter 2: Problem 51 Holt Physics: Student Edition 2009 1

One swimmer in a relay race has a 0.50 s lead and is swimming at a constant speed of 4.00 m/s. The swimmer has 20.0 m to swim before reaching the end of the pool. A second swimmer moves in the same direction as the leader. What constant speed must the second swimmer have in order to catch up to the leader at the end of the pool?

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