Critical Thinking Because of Earths daily rotation, you

Chapter 6: Problem 1 Physics: Principles & Problems 9

A stone is thrown horizontally at a speed of 5.0 m/s from the top of a cliff that is 78.4 m high. a. How long does it take the stone to reach the bottom of the cliff? b. How far from the base of the cliff does the stone hit the ground? c. What are the horizontal and vertical components of the stones velocity just before it hits the ground?

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Chapter 6: Problem 2 Physics: Principles & Problems 9

Lucy and her friend are working at an assembly plant making wooden toy giraffes. At the end of the line, the giraffes go horizontally off the edge of the conveyor belt and fall into a box below. If the box is 0.6 m below the level of the conveyor belt and 0.4 m away from it, what must be the horizontal velocity of giraffes as they leave the conveyor belt?

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Chapter 6: Problem 3 Physics: Principles & Problems 9

You are visiting a friend from elementary school who now lives in a small town. One local amusement is the ice-cream parlor, where Stan, the short-order cook, slides his completed ice-cream sundaes down the counter at a constant speed of 2.0 m/s to the servers. (The counter is kept very well polished for this purpose.) If the servers catch the sundaes 7.0 cm from the edge of the counter, how far do they fall from the edge of the counter to the point at which the servers catch them?

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Chapter 6: Problem 4 Physics: Principles & Problems 9

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Chapter 6: Problem 5 Physics: Principles & Problems 9

The player in problem 4 then kicks the ball with the same speed, but at 60.0 from the horizontal. What is the balls hang time, range, and maximum height?

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Chapter 6: Problem 6 Physics: Principles & Problems 9

A rock is thrown from a 50.0-m-high cliff with an initial velocity of 7.0 m/s at an angle of 53.0 above the horizontal. Find the velocity vector for when it hits the ground below.

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Chapter 6: Problem 7 Physics: Principles & Problems 9

Projectile Motion Two baseballs are pitched horizontally from the same height, but at different speeds. The faster ball crosses home plate within the strike zone, but the slower ball is below the batters knees. Why does the faster ball not fall as far as the slower one?

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Chapter 6: Problem 8 Physics: Principles & Problems 9

Free-Body Diagram An ice cube slides without friction across a table at a constant velocity. It slides off the table and lands on the floor. Draw free-body and motion diagrams of the ice cube at two points on the table and at two points in the air.

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Chapter 6: Problem 9 Physics: Principles & Problems 9

Projectile Motion A softball is tossed into the air at an angle of 50.0 with the vertical at an initial velocity of 11.0 m/s. What is its maximum height?

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Chapter 6: Problem 10 Physics: Principles & Problems 9

Projectile Motion A tennis ball is thrown out a window 28 m above the ground at an initial velocity of 15.0 m/s and 20.0 below the horizontal. How far does the ball move horizontally before it hits the ground?

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Chapter 6: Problem 11 Physics: Principles & Problems 9

Critical Thinking Suppose that an object is thrown with the same initial velocity and direction on Earth and on the Moon, where g is one-sixth that on Earth. How will the following quantities change? a. vx b. the objects time of flight c. ymax d. R

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Chapter 6: Problem 12 Physics: Principles & Problems 9

A runner moving at a speed of 8.8 m/s rounds a bend with a radius of 25 m. What is the centripetal acceleration of the runner, and what agent exerts force on the runner?

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Chapter 6: Problem 13 Physics: Principles & Problems 9

A car racing on a flat track travels at 22 m/s around a curve with a 56-m radius. Find the cars centripetal acceleration. What minimum coefficient of static friction between the tires and road is necessary for the car to round the curve without slipping?

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Chapter 6: Problem 14 Physics: Principles & Problems 9

An airplane traveling at 201 m/s makes a turn. What is the smallest radius of the circular path (in km) that the pilot can make and keep the centripetal acceleration under 5.0 m/s2?

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Chapter 6: Problem 15 Physics: Principles & Problems 9

A 45-kg merry-go-round worker stands on the rides platform 6.3 m from the center. If her speed as she goes around the circle is 4.1 m/s, what is the force of friction necessary to keep her from falling off the platform?

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Chapter 6: Problem 16 Physics: Principles & Problems 9

Uniform Circular Motion What is the direction of the force that acts on the clothes in the spin cycle of a washing machine? What exerts the force?

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Chapter 6: Problem 17 Physics: Principles & Problems 9

Free-Body Diagram You are sitting in the backseat of a car going around a curve to the right. Sketch motion and free-body diagrams to answer the following questions. a. What is the direction of your acceleration? b. What is the direction of the net force that is acting on you? c. What exerts this force?

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Chapter 6: Problem 18 Physics: Principles & Problems 9

Centripetal Force If a 40.0-g stone is whirled horizontally on the end of a 0.60-m string at a speed of 2.2 m/s, what is the tension in the string?

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Chapter 6: Problem 19 Physics: Principles & Problems 9

Centripetal Acceleration A newspaper article states that when turning a corner, a driver must be careful to balance the centripetal and centrifugal forces to keep from skidding. Write a letter to the editor that critiques this article.

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Chapter 6: Problem 20 Physics: Principles & Problems 9

Centripetal Force A bowling ball has a mass of 7.3 kg. If you move it around a circle with a radius of 0.75 m at a speed of 2.5 m/s, what force would you have to exert on it?

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Chapter 6: Problem 21 Physics: Principles & Problems 9

Critical Thinking Because of Earths daily rotation, you always move with uniform circular motion. What is the agent that supplies the force that accelerates you? How does this motion affect your apparent weight?

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Chapter 6: Problem 22 Physics: Principles & Problems 9

You are riding in a bus moving slowly through heavy traffic at 2.0 m/s. You hurry to the front of the bus at 4.0 m/s relative to the bus. What is your speed relative to the street?

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Chapter 6: Problem 23 Physics: Principles & Problems 9

Rafi is pulling a toy wagon through the neighborhood at a speed of 0.75 m/s. A caterpillar in the wagon is crawling toward the rear of the wagon at a rate of 2.0 cm/s. What is the caterpillars velocity relative to the ground?

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Chapter 6: Problem 24 Physics: Principles & Problems 9

A boat is rowed directly upriver at a speed of 2.5 m/s relative to the water. Viewers on the shore see that the boat is moving at only 0.5 m/s relative to the shore. What is the speed of the river? Is it moving with or against the boat?

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Chapter 6: Problem 25 Physics: Principles & Problems 9

An airplane flies due north at 150 km/h relative to the air. There is a wind blowing at 75 km/h to the east relative to the ground. What is the planes speed relative to the ground?

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Chapter 6: Problem 26 Physics: Principles & Problems 9

Relative Velocity A fishing boat with a maximum speed of 3 m/s relative to the water is in a river that is flowing at 2 m/s. What is the maximum speed the boat can obtain relative to the shore? The minimum speed? Give the direction of the boat, relative to the rivers current, for the maximum speed and the minimum speed relative to the shore

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Chapter 6: Problem 27 Physics: Principles & Problems 9

Relative Velocity of a Boat A powerboat heads due northwest at 13 m/s relative to the water across a river that flows due north at 5.0 m/s. What is the velocity (both magnitude and direction) of the motorboat relative to the shore?

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Chapter 6: Problem 28 Physics: Principles & Problems 9

Relative Velocity An airplane flies due south at 175 km/h relative to the air. There is a wind blowing at 85 km/h to the east relative to the ground. What are the planes speed and direction relative to the ground?

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Chapter 6: Problem 29 Physics: Principles & Problems 9

A Planes Relative Velocity An airplane flies due north at 235 km/h relative to the air. There is a wind blowing at 65 km/h to the northeast relative to the ground. What are the planes speed and direction relative to the ground?

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Chapter 6: Problem 30 Physics: Principles & Problems 9

Relative Velocity An airplane has a speed of 285 km/h relative to the air. There is a wind blowing at 95 km/h at 30.0 north of east relative to Earth. In which direction should the plane head to land at an airport due north of its present location? What is the planes speed relative to the ground

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Chapter 6: Problem 31 Physics: Principles & Problems 9

. Critical Thinking You are piloting a boat across a fast-moving river. You want to reach a pier directly opposite your starting point. Describe how you would navigate the boat in terms of the components of your velocity relative to the water.

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Chapter 6: Problem 32 Physics: Principles & Problems 9

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Chapter 6: Problem 33 Physics: Principles & Problems 9

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Chapter 6: Problem 34 Physics: Principles & Problems 9

A student is playing with a radio-controlled race car on the balcony of a sixth-floor apartment. An accidental turn sends the car through the railing and over the edge of the balcony. Does the time it takes the car to fall depend upon the speed it had when it left the balcony?

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Chapter 6: Problem 35 Physics: Principles & Problems 9

An airplane pilot flying at constant velocity and altitude drops a heavy crate. Ignoring air resistance, where will the plane be relative to the crate when the crate hits the ground? Draw the path of the crate as seen by an observer on the ground.

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Chapter 6: Problem 36 Physics: Principles & Problems 9

Can you go around a curve with the following accelerations? Explain. a. zero acceleration b. constant acceleration

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Chapter 6: Problem 37 Physics: Principles & Problems 9

To obtain uniform circular motion, how must the net force depend on the speed of the moving object? (6.2)

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Chapter 6: Problem 38 Physics: Principles & Problems 9

If you whirl a yo-yo about your head in a horizontal circle, in what direction must a force act on the yo-yo? What exerts the force? (6.2)

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Chapter 6: Problem 39 Physics: Principles & Problems 9

Why is it that a car traveling in the opposite direction as the car in which you are riding on the freeway often looks like it is moving faster than the speed limit? (6.3)

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