Question 1

A speed boat requires 80 kW to move at a constant speed of 12 m/s.What is the resistive force of the water at this speed?

Accepted Answer

A)  2700 N 
B)  5300 N 
C)  6700 N 
D)  7700 N

Question 2

A 2000-kg ore car rolls 50.0 m down a frictionless 10.0° incline.If there is a horizontal spring at the end of the incline,what spring constant is required to stop the ore car in a distance of 2.00 m?

Accepted Answer

A)  340 kN/m 
B)  68.1 kN/m 
C)  1700 kN/m 
D)  85.1 kN/m

Question 3

A 20-N crate starting at rest slides down a rough 5.0-m long ramp,inclined at 25° with the horizontal.30 J of energy is lost to friction.What will be the speed of the crate at the bottom of the incline?

Accepted Answer

A)  0.98 m/s 
B)  2.1 m/s 
C)  3.5 m/s 
D)  4.7 m/s

Question 4

A 5.00 kg ball falls from a 2.00 m-high shelf.Just before hitting the floor,what will be its kinetic energy? (g = 9.80 m/s2 and assume air resistance is negligible)

Accepted Answer

A)  98.0 J 
B)  49.0 J 
C)  19.6 J 
D)  10.0 J

Question 5

A baseball outfielder throws a baseball of mass 0.15 kg at a speed of 30 m/s and initial angle of 30°.What is the kinetic energy of the baseball at the highest point of the trajectory? Ignore air friction.

Accepted Answer

A)  zero 
B)  51 J 
C)  92 J 
D)  120 J

Question 6

By how much is the energy stored in a Hooke's law spring increased when its stretch is increased from 4.00 cm to 8.00 cm?

Accepted Answer

A)  100% 
B)  200% 
C)  300 % 
D)  The correct answer is not given.

Question 7

A 1000 kg sports car accelerates from zero to 25 m/s in 6.25 s.What is the average power delivered by the automobile engine?

Accepted Answer

A)  20.8 kW 
B)  30.3 kW 
C)  41.7 kW 
D)  50.0 kW

Question 8

A force of 200 N is applied to a 50-kg mass in the direction of motion for a distance of 6.0 m,and then the force is increased to 300 N for the next 5.0 m.For the 11 m of travel,how much work is done by the varying force?

Accepted Answer

A)  2700 J 
B)  1500 J 
C)  2400 J 
D)  −1200 J

Question 9

A baseball catcher puts on an exhibition by catching a 0.15-kg ball dropped from a helicopter at a height of 91 m.What is the speed of the ball just before it hits the catcher's glove 1.0 m above the ground? (g = 9.8 m/s2 and ignore air resistance)

Accepted Answer

A)  84 m/s 
B)  38 m/s 
C)  42 m/s 
D)  19 m/s

Question 10

Old Faithful geyser in Yellowstone Park shoots water hourly to a height of 30 m.With what velocity does the water leave the ground?

Accepted Answer

A)  7.0 m/s 
B)  14 m/s 
C)  24 m/s 
D)  28 m/s

Question 11

Samantha pushes a 60-N crate up a ramp 20.0 m in length and inclined at 10° with the horizontal.What potential energy change does the crate experience?

Accepted Answer

A)  1200 J 
B)  210 J 
C)  600 J 
D)  300 J

Question 12

A baseball catcher puts on an exhibition by catching a 0.150-kg ball dropped from a helicopter at a height of 100 m above the catcher.If the catcher "gives" with the ball for a distance of 0.500 m while catching it,what average force is exerted on the mitt by the ball? (g = 9.80 m/s2)

Accepted Answer

A)  78 N 
B)  119 N 
C)  197 N 
D)  295 N

Question 13

A jet engine develops 2.0 × 105 N of thrust in moving an airplane forward at a speed of 900 km/h.What is the power developed by the engine?

Accepted Answer

A)  500 kW 
B)  10 MW 
C)  25 MW 
D)  50 MW

Question 14

A spring with spring constant k is used to launch a mass m up a frictionless inclined plane having angle of elevation θ.What is the maximum height reached above the starting elevation of the mass during the motion of the mass if the spring is compressed a distance d before launch?

Accepted Answer

A) 
 
B) 
 
C) 
 
D)

Question 15

A pendulum consists of a mass m suspended from a string of length L.When the pendulum is swinging,how much greater is the mass's potential energy when the string is displaced from the vertical by the angle θ than when the mass is at the lowest position?

Accepted Answer

A)  mgL​sinθ 
B)  mgL​cosθ 
C)  mgL(1 - sinθ) 
D)  mgL(1 - cosθ)

Question 16

Four different compact fluorescent bulbs and their comparison to incandescent bulbs are advertised as follows: a 42-W cfl produces the light of a 150-W incandescent,a 9-W cfl produces the light of a 40-W incandescent,a 23-W cfl produces the light of a 100-W incandescent,and a 13-W cfl produces the light of a 60-W incandescent.Which cfl produces the most light per watt,and which one produces the least? Assume true advertising!

Accepted Answer

A)  the 13 W,the 42 W 
B)  the 9 W,the 23 W 
C)  the 23 W,the 42 W 
D)  the 42 W,the 13 W

Question 17

A simple pendulum,2.0 m in length,is released with a push when the support string is at an angle of 25° from the vertical.If the initial speed of the suspended mass is 2.0 m/s when at the release point,what is its speed at the bottom of the swing? (g = 9.8 m/s2)

Accepted Answer

A)  2.3 m/s 
B)  2.6 m/s 
C)  2.8 m/s 
D)  0.5 m/s

Question 18

A 100-W light bulb is left on for 20.0 hours.Over this period of time,how much energy did the bulb use?

Accepted Answer

A)  1000 J 
B)  7.2 MJ 
C)  3,600,000 J 
D)  1.34 hp

Question 19

A pile driver drives a post into the ground.The mass of the pile driver is 2500 kg,and it is dropped through a height of 8.0 m on each stroke.If the resisting force of the ground is 2.0 × 106 N,how far is the post driven in on each stroke?

Accepted Answer

A)  4.9 cm 
B)  9.9 cm 
C)  16 cm 
D)  49 cm

Question 20

A girl and her bicycle have a total mass of 40.0 kg.At the top of the hill her speed is 5.0 m/s,and her speed doubles as she rides down the hill.The hill is 12.0 m high and 100 m long.How much kinetic energy and potential energy is lost to friction?

Accepted Answer

A)  2420 J 
B)  3200 J 
C)  2000 J 
D)  3920 J

Exam 6: Momentum and Collisions: Part A

A speed boat requires 80 kW to move at a constant speed of 12 m/s.What is the resistive force of the water at this speed?

A 2000-kg ore car rolls 50.0 m down a frictionless 10.0° incline.If there is a horizontal spring at the end of the incline,what spring constant is required to stop the ore car in a distance of 2.00 m?

A 20-N crate starting at rest slides down a rough 5.0-m long ramp,inclined at 25° with the horizontal.30 J of energy is lost to friction.What will be the speed of the crate at the bottom of the incline?

A 5.00 kg ball falls from a 2.00 m-high shelf.Just before hitting the floor,what will be its kinetic energy? (g = 9.80 m/s² and assume air resistance is negligible)

A baseball outfielder throws a baseball of mass 0.15 kg at a speed of 30 m/s and initial angle of 30°.What is the kinetic energy of the baseball at the highest point of the trajectory? Ignore air friction.

By how much is the energy stored in a Hooke's law spring increased when its stretch is increased from 4.00 cm to 8.00 cm?

A 1000 kg sports car accelerates from zero to 25 m/s in 6.25 s.What is the average power delivered by the automobile engine?

A force of 200 N is applied to a 50-kg mass in the direction of motion for a distance of 6.0 m,and then the force is increased to 300 N for the next 5.0 m.For the 11 m of travel,how much work is done by the varying force?

A baseball catcher puts on an exhibition by catching a 0.15-kg ball dropped from a helicopter at a height of 91 m.What is the speed of the ball just before it hits the catcher's glove 1.0 m above the ground? (g = 9.8 m/s² and ignore air resistance)

Old Faithful geyser in Yellowstone Park shoots water hourly to a height of 30 m.With what velocity does the water leave the ground?

Samantha pushes a 60-N crate up a ramp 20.0 m in length and inclined at 10° with the horizontal.What potential energy change does the crate experience?

A baseball catcher puts on an exhibition by catching a 0.150-kg ball dropped from a helicopter at a height of 100 m above the catcher.If the catcher "gives" with the ball for a distance of 0.500 m while catching it,what average force is exerted on the mitt by the ball? (g = 9.80 m/s²)

A jet engine develops 2.0 × 10⁵ N of thrust in moving an airplane forward at a speed of 900 km/h.What is the power developed by the engine?

A spring with spring constant k is used to launch a mass m up a frictionless inclined plane having angle of elevation θ.What is the maximum height reached above the starting elevation of the mass during the motion of the mass if the spring is compressed a distance d before launch?

A pendulum consists of a mass m suspended from a string of length L.When the pendulum is swinging,how much greater is the mass's potential energy when the string is displaced from the vertical by the angle θ than when the mass is at the lowest position?

A simple pendulum,2.0 m in length,is released with a push when the support string is at an angle of 25° from the vertical.If the initial speed of the suspended mass is 2.0 m/s when at the release point,what is its speed at the bottom of the swing? (g = 9.8 m/s²)

A 100-W light bulb is left on for 20.0 hours.Over this period of time,how much energy did the bulb use?

A pile driver drives a post into the ground.The mass of the pile driver is 2500 kg,and it is dropped through a height of 8.0 m on each stroke.If the resisting force of the ground is 2.0 × 10⁶ N,how far is the post driven in on each stroke?

A girl and her bicycle have a total mass of 40.0 kg.At the top of the hill her speed is 5.0 m/s,and her speed doubles as she rides down the hill.The hill is 12.0 m high and 100 m long.How much kinetic energy and potential energy is lost to friction?