Question 1

The angle between the vectors  = -2  + 3  and  = 4  - 5  is approximately

Accepted Answer

A)  5º 
B)  47º 
C)  175º 
D)  15º 
E)  26º

Question 2

A motor develops power as shown in the graph. The energy expended by the motor in the time interval between t = 10 s and t = 30 s is

Accepted Answer

A)  1.0 J 
B)  1.3 J 
C)  0.20 kJ 
D)  0.60 kJ 
E)  0.70 kJ

Question 3

A body is acted upon by a force of 10 N and undergoes displacement in the direction of the force in accordance with the relation
S = 3t2 + 2t
Where the units are SI. The rate at which the force is doing work at the instant t = 2 s is

Accepted Answer

A)  14 W 
B)  12 W 
C)  120 W 
D)  140 W 
E)  160 W

Question 4

A hydroelectric power plant generates electricity from water falling a height of h m and at a rate of 20,000 kg/s. If the theoretical maximum power output of the plant is 15.0 MW what is the height h?

Accepted Answer

A)  750 m 
B)  153 m 
C)  102 m 
D)  76.5 m 
E)  38.3 m

Question 5

In a television tube, an electron starting from rest experiences a force of 4.0 $\times$ 10-15 N over a distance of 50 cm. The final speed of the electron is (do not worry about relativistic effects):

Accepted Answer

A)  4.4 $\times$ 1015 m/s 
B)  6.6 $\times$ 107 m/s 
C)  3.3 $\times$ 107 m/s 
D)  1.3 $\times$ 108 m/s 
E)  6.6 $\times$ 108 m/s

Question 6

Kids love to crash their toy cars together. One such collision involves a 0.5 kg car moving at 0.3 m/s colliding with a stationary toy car of mass 0.3 kg. The two toys stick together and move away from the collision point at 0.188 m/s. By what factor is the initial kinetic energy greater than the final kinetic energy?

Accepted Answer

A)  0.63 
B)  1.6 
C)  2.5 
D)  4.2 
E)  1.0 The kinetic energy stays the same.

Question 7

What is the work done by a car's braking system when it slows the 1500-kg car from an initial speed of 96 km/h down to 56 km/h in a distance of 55 m?

Accepted Answer

A)  8.3 kJ 
B)  20 kJ 
C)  1.3 MJ 
D)  2.5 MJ 
E)  8.3 MJ

Question 8

A Blackhawk helicopter is winching up an injured soldier from a danger zone. The soldier and his kit have a mass of 150 kg and are pulled up 50 m in the air at a steady rate. If it takes 30 s to pull the soldier up, how much power has been used by the helicopter's 65% efficient winch engine?

Accepted Answer

A)  2.5 kW 
B)  3.8 kW 
C)  1.6 kW 
D)  4.1 kW 
E)  3.2 kW

Question 9

If the average power output of a car engine is the same as a 100-W light bulb, how long would it take a 1200-kg car to go from zero to 96 km/h (60 mph)?

Accepted Answer

A)  8.5 $\times$ 103 s 
B)  5.5 $\times$ 104 s 
C)  65 s 
D)  160 s 
E)  4.3 $\times$ 103 s

Question 10

Two parents moving into a new house attempt to pull a large crate down a large hallway. One parent applies a force of magnitude 150 N directed 45 degrees to the direction of motion, while the other parent applies a force of 120 N on the other side of the direction of motion. If they move the crate 15 m and perform work at 2.6 kJ, at what angle to the direction of motion did the second parent pull on the crate?

Accepted Answer

A)  54 degrees 
B)  30 degrees 
C)  60 degrees 
D)  34 degrees 
E)  56 degrees

Question 11

What minimum power rating must a water pump have if needs to raise water at 20 kg per minute from a depth of 9 m?

Accepted Answer

A)  1.76 kW 
B)  29.4 W 
C)  106 kW 
D)  3.0 W 
E)  180 W

Question 12

A force  pushes a block along a horizontal surface against a force of friction  f. If the block undergoes a displacement s at constant velocity, the work done by the resultant force on the block

Accepted Answer

A)  is equal to the work done by the force of friction  f 
B)  is given by W =  ·  
C)  increases the kinetic energy of the block. 
D)  increases the potential energy of the block. 
E)  is zero.

Question 13

A bullet with a mass of 12 g moving horizontally strikes a fixed block of wood and penetrates a distance of 5.2 cm. The speed of the bullet just before the collision is 640 m/s. The average force that the wood exerted on the bullet was

Accepted Answer

A)  4.7 $\times$ 104 N 
B)  74 N 
C)  4.7 $\times$ 106 N 
D)  unknown; the mass of the wood is required 
E)  None of these is correct.

Question 14

A body moves with decreasing speed. Which of the following statements is true?

Accepted Answer

A)  The net work done on the body is positive, and the kinetic energy is increasing. 
B)  The net work done on the body is positive, and the kinetic energy is decreasing. 
C)  The net work done on the body is zero, and the kinetic energy is decreasing. 
D)  The net work done on the body is negative, and the kinetic energy is increasing. 
E)  The net work done on the body is negative, and the kinetic energy is decreasing.

Question 15

The average marathon runner can complete the 42.2-km distance of the marathon in 3 h and 30 min. If the runner's mass is 75 kg, what is the runner's average kinetic energy during the run?

Accepted Answer

A)  842 J 
B)  5.45 $\times$ 103 J 
C)  251 J 
D)  126 J 
E)  421 J

Question 16

The angle between the vector  =  + 2  + 3k and the x axis is approximately

Accepted Answer

A)  17º 
B)  26º 
C)  37º 
D)  58º 
E)  75º

Question 17

A 6.0-kg block slides from point A down a frictionless curve to point B. After the block passes point B, a friction force opposes the motion of the block so that it comes to a stop 2.5 m from B. Calculate the coefficient of kinetic friction between the block and the surface after position B.

Accepted Answer

A)  2.5 
B)  0.40 
C)  >0.40 
D)  0.40 N 
E)  2.5 N

Question 18

The human heart is essentially a pump for moving blood around the body. If its average power output (over many beats) is about 2.0 W and it pumps blood at an overall average speed of 0.3 m/s into the output aorta channel, calculate the average force with which the heart moves the blood into the aorta.

Accepted Answer

A)  0.60 N 
B)  6.7 N 
C)  22 N 
D)  66 N 
E)  0.18 N

Question 19

Use the figure to answer the next question. A light rope runs through two frictionless pulleys of negligible mass. A mass, m, is hung from one of the pulleys and a force, F is applied to one end of the rope so that the mass moves at a constant speed. 
-A car and its occupants, with a total mass m, are moving at a speed v relative to an observer on the side of the road. You are driving in another car, also traveling at speed v, and in the same direction as the first car. The kinetic energy of the first car relative to you is

Accepted Answer

A)  0 
B)   mv2 
C)   m(2v)2 
D)   m (3v)2 
E)  depends on the mass of your car

Question 20

Power P is required to lift a body a distance d at a constant speed v. What power is required to lift the body a distance 2d at constant speed 3v?

Accepted Answer

A)  P 
B)  2P 
C)  3P 
D)  6P 
E)  3P/2

Exam 6: Work and Energy

The angle between the vectors = -2 + 3 and = 4 - 5 is approximately

A motor develops power as shown in the graph. The energy expended by the motor in the time interval between t = 10 s and t = 30 s is

A body is acted upon by a force of 10 N and undergoes displacement in the direction of the force in accordance with the relation S = 3t² + 2t Where the units are SI. The rate at which the force is doing work at the instant t = 2 s is

A hydroelectric power plant generates electricity from water falling a height of h m and at a rate of 20,000 kg/s. If the theoretical maximum power output of the plant is 15.0 MW what is the height h?

In a television tube, an electron starting from rest experiences a force of 4.0 $\times$ 10^-15N over a distance of 50 cm. The final speed of the electron is (do not worry about relativistic effects) :

What is the work done by a car's braking system when it slows the 1500-kg car from an initial speed of 96 km/h down to 56 km/h in a distance of 55 m?

A Blackhawk helicopter is winching up an injured soldier from a danger zone. The soldier and his kit have a mass of 150 kg and are pulled up 50 m in the air at a steady rate. If it takes 30 s to pull the soldier up, how much power has been used by the helicopter's 65% efficient winch engine?

If the average power output of a car engine is the same as a 100-W light bulb, how long would it take a 1200-kg car to go from zero to 96 km/h (60 mph) ?

What minimum power rating must a water pump have if needs to raise water at 20 kg per minute from a depth of 9 m?

A force pushes a block along a horizontal surface against a force of friction _f. If the block undergoes a displacement s at constant velocity, the work done by the resultant force on the block

A bullet with a mass of 12 g moving horizontally strikes a fixed block of wood and penetrates a distance of 5.2 cm. The speed of the bullet just before the collision is 640 m/s. The average force that the wood exerted on the bullet was

A body moves with decreasing speed. Which of the following statements is true?

The average marathon runner can complete the 42.2-km distance of the marathon in 3 h and 30 min. If the runner's mass is 75 kg, what is the runner's average kinetic energy during the run?

The angle between the vector = + 2 + 3k and the x axis is approximately

A 6.0-kg block slides from point A down a frictionless curve to point B. After the block passes point B, a friction force opposes the motion of the block so that it comes to a stop 2.5 m from B. Calculate the coefficient of kinetic friction between the block and the surface after position B.

Power P is required to lift a body a distance d at a constant speed v. What power is required to lift the body a distance 2d at constant speed 3v?

Exam 6: Work and Energy

The angle between the vectors = -2 + 3 and = 4 - 5 is approximately

A motor develops power as shown in the graph. The energy expended by the motor in the time interval between t = 10 s and t = 30 s is

A body is acted upon by a force of 10 N and undergoes displacement in the direction of the force in accordance with the relation S = 3t2 + 2t Where the units are SI. The rate at which the force is doing work at the instant t = 2 s is

A hydroelectric power plant generates electricity from water falling a height of h m and at a rate of 20,000 kg/s. If the theoretical maximum power output of the plant is 15.0 MW what is the height h?

In a television tube, an electron starting from rest experiences a force of 4.0 ×\times× 10-15 N over a distance of 50 cm. The final speed of the electron is (do not worry about relativistic effects) :

What is the work done by a car's braking system when it slows the 1500-kg car from an initial speed of 96 km/h down to 56 km/h in a distance of 55 m?

A Blackhawk helicopter is winching up an injured soldier from a danger zone. The soldier and his kit have a mass of 150 kg and are pulled up 50 m in the air at a steady rate. If it takes 30 s to pull the soldier up, how much power has been used by the helicopter's 65% efficient winch engine?

If the average power output of a car engine is the same as a 100-W light bulb, how long would it take a 1200-kg car to go from zero to 96 km/h (60 mph) ?

What minimum power rating must a water pump have if needs to raise water at 20 kg per minute from a depth of 9 m?

A force pushes a block along a horizontal surface against a force of friction f. If the block undergoes a displacement s at constant velocity, the work done by the resultant force on the block

A bullet with a mass of 12 g moving horizontally strikes a fixed block of wood and penetrates a distance of 5.2 cm. The speed of the bullet just before the collision is 640 m/s. The average force that the wood exerted on the bullet was

A body moves with decreasing speed. Which of the following statements is true?

The average marathon runner can complete the 42.2-km distance of the marathon in 3 h and 30 min. If the runner's mass is 75 kg, what is the runner's average kinetic energy during the run?

The angle between the vector = + 2 + 3k and the x axis is approximately

A 6.0-kg block slides from point A down a frictionless curve to point B. After the block passes point B, a friction force opposes the motion of the block so that it comes to a stop 2.5 m from B. Calculate the coefficient of kinetic friction between the block and the surface after position B.

Power P is required to lift a body a distance d at a constant speed v. What power is required to lift the body a distance 2d at constant speed 3v?

A body is acted upon by a force of 10 N and undergoes displacement in the direction of the force in accordance with the relation S = 3t² + 2t Where the units are SI. The rate at which the force is doing work at the instant t = 2 s is

In a television tube, an electron starting from rest experiences a force of 4.0 $\times$ 10^-15N over a distance of 50 cm. The final speed of the electron is (do not worry about relativistic effects) :

A force pushes a block along a horizontal surface against a force of friction _f. If the block undergoes a displacement s at constant velocity, the work done by the resultant force on the block