Chapter 2

An object is moving along a straight line. The graph shows the object's position from the starting point as a function of time. What was the instantaneous velocity of the object at t = 4 s?

+10 m/s

At time t = 0 s, an object is observed at x = 0 m; and its position along the x axis follows this expression: x = -4t + t2, where the units for distance and time are meters and seconds, respectively. What is the object's displacement Δx between t = 1.0 s and t = 3.0 s?

+16 m

Carl Lewis set a world record for the 100.0-m run with a time of 9.86 s. If, after reaching the finish line, Mr. Lewis walked directly back to his starting point in 90.9 s, what is the magnitude of his average velocity for the 200.0 m?

0 m/s

The graph shows the height versus time of an object. Estimate the instantaneous velocity, in m/s, of the object at time t = 15 min.

0.10 m/s

An object is moving along a straight line. The graph shows the object's velocity as a function of time. How far does the object move in the interval from t = 0 to t = 2 s?

10 m

A train with a constant velocity of +28.6 m/s approaches a small town . The operator applies the brake, reducing the train's velocity to +11.4 m/s. If the average acceleration of the train during braking is -1.35 m/s2, for what elapsed time does the operator apply the brake?

12.7 s

Ryan throws a tennis ball vertically upward. The ball returns to the point of release after 3.5 s. What is the speed of the ball as it is released?

17 m/s

During the first 18 minutes of a 1.0-hour trip, a car has an average speed of 11 m/s. What must the average speed of the car be during the last 42 minutes of the trip be if the car is to have an average speed of 21 m/s for the entire trip?

25 m/s

A rock, dropped from rest near the surface of an atmosphere-free planet, attains a speed of 20.0 m/s after falling 8.0 meters. What is the magnitude of the acceleration due to gravity on the surface of this planet?

25 m/s2

A rock, dropped from rest near the surface of an atmosphere-free planet, attains a speed of 20.0 m/s after falling 8.0 meters. Determine the speed of the object after falling from rest through 16 m on this planet.

28 m/s

The figure shows the speed as a function of time for an object in free fall near the surface of the earth. The object was dropped from rest in a long evacuated cylinder. What is the speed of the object 3.0 seconds after it is dropped?

29 m/s

A turtle takes 3.5 minutes to walk 18 m toward the south along a deserted highway. A truck driver stops and picks up the turtle. The driver takes the turtle to a town 1.1 km to the north with an average speed of 12 m/s. What is the magnitude of the average velocity of the turtle for its entire journey?

3.6 m/s

A ball is dropped from rest from a tower and strikes the ground 110 m below. Approximately how many seconds does it take the ball to strike the ground after being dropped? Neglect air resistance.

4.74 s

A car starts from rest and accelerates at a constant rate in a straight line. In the first second the car moves a distance of 2.0 meters. How much additional distance will the car move during the second second of its motion?

6.0 m

Neglecting air resistance, what maximum height will be reached by an arrow launched straight upward with an initial speed of 35 m/s?

63 m

A car traveling along a road begins accelerating with a constant acceleration of 1.5 m/s2 in the direction of motion. After traveling 392 m at this acceleration, its speed is 35 m/s. Determine the speed of the car when it began accelerating.

7.0 m/s

Ball A is dropped from rest from a window. At the same instant, ball B is thrown downward; and ball C is thrown upward from the same window. Which statement concerning the balls after their release is necessarily true if air resistance is neglected?

All three balls have the same acceleration at any instant

wo cars travel along a level highway. It is observed that the distance between the cars is increasing. Which one of the following statements concerning this situation is necessarily true?

Both cars could be accelerating at the same rate.

An object is moving along a straight line in the positive x direction. The graph shows its position from the starting point as a function of time. Various segments of the graph are identified by the letters A, B, C, and D. Which segment(s) of the graph represent(s) a constant velocity of +1.0 m/s?

D

The figure shows the speed as a function of time for an object in free fall near the surface of the earth. The object was dropped from rest in a long evacuated cylinder. If the same object were released in air, the magnitude of its acceleration would begin at the free-fall value, but it would decrease continuously to zero as the object continued to fall. For which one of the choices given does the solid line best represent the speed of the object as a function of time when it is dropped from rest in air? Note: The dashed line shows the free-fall under vacuum graph for comparison.

E

Two objects A and B accelerate from rest with the same constant acceleration. Object A accelerates for twice as much time as object B, however. Which one of the following statements is true concerning these objects at the end of their respective periods of acceleration?

Object A will travel four times as far as object B.

An object moving along a straight line is decelerating. Which one of the following statements concerning the object's acceleration is necessarily true?

The direction of the acceleration is in the direction opposite to that of the velocity

A particle travels along a curved path between two points P and Q as shown. The displacement of the particle does not depend on

the distance traveled from P to Q

What is the acceleration of the object at t = 7.0 s?

zero m/s2

A automotive test driver travels due north in a prototype hybrid vehicle at 30 mi/h for 2 hours. She then reverses her direction and travels due south at 60 mi/h for 1 hour. What is the average velocity of the vehicle?

zero mi/h

In a race, Marcos runs 1.00 mile in 4.02 min, mounts a bicycle, and rides back to his starting point, which is also the finish line, in 3.02 min. What is the magnitude of Marcos' average velocity for the race?

zero mi/h

What is the total distance that the bug traveled between t = 0.00 s and t = 20.0 s? Assume the bug only changed directions at the end of a five-second interval.

39.9 cm

An object is moving along a straight line. The graph shows the object's position from the starting point as a function of time. At which time or times does the object reverse its direction of motion?

5 s

A tennis ball is shot vertically upward in an evacuated chamber inside a tower with an initial speed of 20.0 m/s at time t = 0 s. Determine the velocity of the ball at t = 3.00 seconds.

9.40 m/s, downward

The figure shows the speed as a function of time for an object in free fall near the surface of the earth. The object was dropped from rest in a long evacuated cylinder. What is the numerical value of the slope of the line?

9.8 m/s2

A car is moving at a constant velocity when it is involved in a collision. The car comes to rest after 0.450 s with an average acceleration of 60.0 m/s2 in the direction opposite that of the car's velocity. What was the speed, in km/h, of the car before the collision?

97.2 km/h

An object is moving along a straight line. The graph shows the object's velocity as a function of time. What is the acceleration of the object in the interval from t = 5 s to t = 6 s?

-10 m/s2

Determine the velocity of the ball when it returns to its original position. Note: assume the upward direction is positive.

-20 m/s

An object is moving along the x axis. The graph shows its position from the starting point as a function of time. Various segments of the graph are identified by the letters A, B, C, and D. What is the velocity of the object at t = 7.0 s?

-3.0 m/s

A pitcher delivers a fast ball with a velocity of 43 m/s to the south. The batter hits the ball and gives it a velocity of 51 m/s to the north. What was the average acceleration of the ball during the 1.0 ms when it was in contact with the bat?

9.4 × 104 m/s2, north

A rock, dropped from rest near the surface of an atmosphere-free planet, attains a speed of 20.0 m/s after falling 8.0 meters. How long did it take the object to fall the 8.0 meters mentioned?

0.80 s

A brick is dropped from rest from a height of 4.9 m. How long does it take the brick to reach the ground?

1.0 s

A rock, dropped from rest near the surface of an atmosphere-free planet, attains a speed of 20.0 m/s after falling 8.0 meters. How long would it take the object, falling from rest, to fall 16 m on this planet?

1.1 s

A train with a constant speed of 16 m/s passes through a town. After leaving the town, the train accelerates at 0.33 m/s2 until it reaches a speed of 35 m/s. How far did the train travel while it was accelerating?

1.5 km

A ball is shot straight up from the surface of the earth with an initial speed of 19.6 m/s. Neglect any effects due to air resistance. What is the magnitude of the ball's displacement from the starting point after 1.00 second has elapsed?

14.7 m

Water drips from rest from a leaf that is 15 meters above the ground. Neglecting air resistance, what is the speed of each water drop when it hits the ground?

17 m/s

A ball is shot straight up from the surface of the earth with an initial speed of 19.6 m/s. Neglect any effects due to air resistance. What maximum height will the ball reach?

19.6 m

An object is moving along a straight line. The graph shows the object's velocity as a function of time. During which interval(s) of the graph does the object travel equal distances in equal times?

2 s to 3 s

An elevator is moving upward with a speed of 11 m/s. Three seconds later, the elevator is still moving upward, but its speed has been reduced to 5.0 m/s. What is the average acceleration of the elevator during the 3.0 s interval?

2.0 m/s2, downward

A tennis ball is shot vertically upward in an evacuated chamber inside a tower with an initial speed of 20.0 m/s at time t = 0 s. Approximately how long does it take the tennis ball to reach its maximum height?

2.04 s

An object starts from rest and accelerates uniformly in a straight line in the positive x direction. After 11 seconds, its speed is 70.0 m/s. How far does the object travel in the first 11 seconds

390 m

A brass ball is shot vertically upward from the surface of an atmosphere-free planet with an initial speed of 20.0 m/s. One second later, the ball has an instantaneous velocity in the upward direction of 15.0 m/s. How long does it take the ball to reach its maximum height?

4.0 s

A hammer is accidentally dropped from rest down a vertical mine shaft. How long does it take for the rock to reach a depth of 79 m? Neglect air resistance.

4.0 s

A ball is shot straight up from the surface of the earth with an initial speed of 19.6 m/s. Neglect any effects due to air resistance. How much time elapses between the throwing of the ball and its return to the original launch point?

4.00 s

A landing airplane makes contact with the runway with a speed of 75.0 m/s and moves toward the south. After 18.5 seconds, the airplane comes to rest. What is the average acceleration of the airplane during the landing?

4.05 m/s2, north

A rock is dropped from rest from a height h above the ground. It falls and hits the ground with a speed of 11 m/s. From what height should the rock be dropped so that its speed on hitting the ground is 22 m/s? Neglect air resistance.

4.0h

A automotive test driver travels due north in a prototype hybrid vehicle at 30 mi/h for 2 hours. She then reverses her direction and travels due south at 60 mi/h for 1 hour. What is the average speed of the vehicle?

40 mi/h

A brass ball is shot vertically upward from the surface of an atmosphere-free planet with an initial speed of 20.0 m/s. One second later, the ball has an instantaneous velocity in the upward direction of 15.0 m/s. How high does the ball rise?

40.0 m

A brass ball is shot vertically upward from the surface of an atmosphere-free planet with an initial speed of 20.0 m/s. One second later, the ball has an instantaneous velocity in the upward direction of 15.0 m/s. What is the magnitude of the acceleration due to gravity on the surface of this planet?

5.0 m/s2

A car starts from rest and accelerates at a constant rate in a straight line. In the first second the car moves a distance of 2.0 meters. How fast will the car be moving at the end of the second second?

8.0 m/s

How long is the ball in the air when it returns to its original position?

8.0 s

A Canadian goose flew 845 km from Southern California to Oregon with an average speed of 28.0 m/s. How long, in hours, did it take the goose to make this journey?

8.38 h

A small object is released from rest and falls 1.00 × 102 feet near the surface of the earth. Neglect air resistance. Approximately how fast will the object be moving after falling through the 1.00 × 102 feet mentioned?

80 ft/s

A race car has a speed of 80 m/s when the driver releases a drag parachute. If the parachute causes a deceleration of -4 m/s2, how far will the car travel before it stops?

800 m

Which one of the following situations is not possible? A) A body has zero velocity and non-zero acceleration. B) A body travels with a northward velocity and a northward acceleration. C) A body travels with a northward velocity and a southward acceleration. D) A body travels with a constant velocity and a time-varying acceleration. E) A body travels with a constant acceleration and a time-varying velocity.

A body travels with a constant velocity and a time-varying acceleration

A ball is thrown vertically upward from the surface of the earth. The ball rises to some maximum height and falls back toward the surface of the earth. Which one of the following statements concerning this situation is true if air resistance is neglected?

The ball is a freely falling body for the duration of its flight.

The figure shows the speed as a function of time for an object in free fall near the surface of the earth. The object was dropped from rest in a long evacuated cylinder. Which one of the following statements best explains why the graph goes through the origin?

The object was dropped from rest

Starting from rest, a particle that is confined to move along a straight line is accelerated at a rate of 5.0 m/s2. Which statement concerning the slope of the position versus time graph for this particle is true?

The slope is not constant and increases with increasing time.

Starting from rest, a particle confined to move along a straight line is accelerated at a rate of 5.0 m/s2. Which one of the following statements accurately describes the motion of this particle?

The speed of the particle increases by 5.0 m/s during each second

A automotive test driver travels due north in a prototype hybrid vehicle at 30 mi/h for 2 hours. She then reverses her direction and travels due south at 60 mi/h for 1 hour. What is the speed of the particle after it has traveled 8 m?

8 m/s

A tennis ball is shot vertically upward in an evacuated chamber inside a tower with an initial speed of 20.0 m/s at time t = 0 s. How high does the ball rise?

20.4 m

An object starts from rest and accelerates uniformly in a straight line in the positive x direction. After 11 seconds, its speed is 70.0 m/s. What is the average velocity of the object during the first 11 seconds?

+35 m/s

An object starts from rest and accelerates uniformly in a straight line in the positive x direction. After 11 seconds, its speed is 70.0 m/s. Determine the acceleration of the object.

+6.4 m/s2

An object is moving along a straight line. The graph shows the object's velocity as a function of time. During which interval(s) of the graph does the speed of the object increase by equal amounts in equal times?

0 s to 2 s and 3 s to 5 s

A car is stopped at a red traffic light. When the light turns to green, the car has a constant acceleration and crosses the 9.10-m intersection in 2.86 s. What is the magnitude of the car's acceleration?

2.23 m/s2

A small object is released from rest and falls 1.00 × 102 feet near the surface of the earth. Neglect air resistance. How long will it take to fall through the 1.00 × 102 feet mentioned?

2.49 s

The minimum takeoff speed for a certain airplane is 75 m/s. What minimum acceleration is required if the plane must leave a runway of length 1050 m? Assume the plane starts from rest at one end of the runway.

2.7 m/s2

A car is initially traveling at 50.0 km/h. The brakes are applied and the car stops over a distance of 35 m. What was magnitude of the car's acceleration while it was braking?

2.8 m/s2

A cheetah is walking at a speed of 1.15 m/s when it observes a gazelle 43.0 m directly ahead. If the cheetah accelerates at 9.25 m/s2, how long does it take the cheetah to reach the gazelle if the gazelle doesn't move?

2.93 s

A automotive test driver travels due north in a prototype hybrid vehicle at 30 mi/h for 2 hours. She then reverses her direction and travels due south at 60 mi/h for 1 hour. After 10 seconds, how far will the particle have traveled?

200 m