PHY 102 Practice 4

A ball player wishes to determine pitching speed by throwing a ball horizontally from an elevation of 4 m above the ground. The player sees the ball land 23 m down range. What is the player's pitching speed in m/s? Round your answer to 1 decimal place. Hint: think back to the section on kinematics and the distance an object falls in a certain time.

25.5

A 1311 kg car accelerates at a rate of 8 m/s/s over a distance of 115 m. What is the work done in Joules to accelerate the car? Round your answer to 1 decimal place.

297393.8

The kinetic energy of a 0.4 kg baseball thrown at a velocity of 46 m/s is _________. Round your answer to 1 decimal place.

423.2 J

A 1736 kg car is moving at 53 km/h. If a 3598 kg truck has 7 times the kinetic energy of the car, how fast is the truck moving in km/h? Round your answer to 1 decimal place.

97.4

A hunter on level ground fires a bullet at an angle of 10 degrees above the horizontal while simultaneously dropping another bullet from the level of the rifle. Which bullet will hit the ground first? A. The dropped one. B. The fired one. C. Both hit at the same time. D. Not enough information to determine.

A

If you push for a half hour or a whole hour against a stationary wall A. no work on the wall is done in either case. B. half as much work is done during the half hour. C. twice as much work is done during the half hour. D. it is impossible to determine how much work is done.

A

A 1000-kg car and a 2000-kg car are hoisted the same distance. Raising the more massive car requires A. less work. B. the same amount of work. C. twice as much work. D. four times as much work. E. more than four times as much work.

C

A bullet fired horizontally over level ground hits the ground in 0.5 second. If it had been fired with twice the speed in the same direction, it would have hit the ground in A. less than 0.5 s. B. more than 0.5 s. C. 0.5 s. D. not enough information.

C

Negative work means A. the kinetic energy of the object increases. B. nothing; there is no such thing as negative work. C. the object has negative velocity. D. the kinetic energy of the object decreases. E. the object does not move.

D

True or False: Two identical projectiles are launched with equal speeds from the top of a building and feel no air resistance. Projectile A is launched above the horizontal while projectile B is launched below the horizontal. Both projectiles have exactly the same acceleration while they are in the air. A. True B. False

A

True or False: You throw a 5.0 kg stone from the top of a cliff with an initial vertical velocity of 8.0 m/s downward and an initial horizontal velocity of 7.0 m/s away from the cliff, and it feels no air resistance. After the stone is in the air but free of your hand, its acceleration remains constant at 9.8 m/s/s downward but its speed changes. A. True B. False

A

It takes 40 J to push a large box 4 m across a floor. Assuming the push is in the same direction as the move, what is the magnitude of the force on the box? A. 4 N B. 10 N C. 40 N D. 160 N E. none of these

B

True or False: A grasshopper leaps into the air at a 62 degree angle above the horizontal. At its highest point, the grasshopper's velocity and acceleration are equal to zero. A. True B. False

B

True or False: A tennis ball following a parabolic trajectory without air resistance has two forces acting on it; gravity downward and a force keeping it moving forward. A. True B. False

B

Energy of motion is ______ energy.

kinetic