Question 1

A pile driver drives a post into the ground.The mass of the pile driver is 2,700 kg and it is dropped through a height of 8.0 m on each stroke.If the resisting force of the ground is 3.0 × 106 N,how far is the post driven in on each stroke?

Accepted Answer

A)   7.1 cm
B)   0.7 cm
C)   0.1 cm
D)   63.5 cm
E)   ​8.1 cm A

Question 2

0.8A satellite is held in orbit by a 1,000-N gravitational force.Each time the satellite completes an orbit of circumference 80,000 km,the work done on it by gravity is:

Accepted Answer

A)   0.8×108 J.
B)   0.8×1011 J.
C)   0.13×108 J.
D)   0.
E)   ​0.13×1011 J. D

Question 3

A block is projected with speed v across a horizontal surface and slides to a stop due to friction.The same block is then projected with the same speed v up an incline where is slides to a stop due to friction.In which case did the total mechanical energy of the block decrease the least?

Accepted Answer

A)   This problem cannot be solved since it was not indicated whether the horizontal surface and the incline both had the same coefficient of kinetic friction.
B)   The case on the horizontal surface had the least decrease in total mechanical energy.
C)   The case on the inclined surface had the least decrease in total mechanical energy.
D)   In both cases the decrease in mechanical energy was the same. C

Question 4

A Hooke's law spring is compressed 12.0 cm from equilibrium and the potential energy stored is 72.0 J.What is the spring constant in this case?

Accepted Answer

A)   10000 N/m
B)   5000 N/m
C)   100 N/m
D)   ​1 N/m
E)   ​No answer is correct.

Question 5

The work done by static friction can be:

Accepted Answer

A)   positive.
B)   negative.
C)   zero.
D)   Any of the above.

Question 6

A 1,200-kg automobile moving at 29 m/s has the brakes applied with a deceleration of 3.0 m/s2.How far does the car travel before it stops?

Accepted Answer

A)   140 m
B)   280 m
C)   504600 m
D)   31200 m
E)   ​400 m

Question 7

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)   12 m/s
B)   17 m/s
C)   20 m/s
D)   24 m/s
E)   ​588 m/s

Question 8

A golf ball hits a wall and bounces back at 1/3 the original speed.What part of the original kinetic energy of the ball did it lose in the collision?

Accepted Answer

A)   2/3
B)   1/6
C)   8/9
D)   1/9
E)   ​1/3

Question 9

A 100-W light bulb is left on for 10.0 hours.Over this period of time,how much energy was used by the bulb?

Accepted Answer

A)   1 000 J
B)   360 000 J
C)   3 600 000 J
D)   1.34 hp
E)   ​36 000 J

Question 10

Samantha pushes a 50-N crate up a ramp 25 m in length and inclined at 10° with the horizontal.What potential energy change does the crate experience?

Accepted Answer

A)   1,231 J
B)   1,250 J
C)   12 J
D)   217 J
E)   ​7,198 J

Question 11

Three different mass projectiles are launched from the top of a building each at different angles of elevation.Each particle has the same initial kinetic energy.Which particle has the greatest kinetic energy just as it impacts with the ground?

Accepted Answer

A)   The one launched at the highest angle of elevation.
B)   The one with the highest mass.
C)   The one with the lowest mass.
D)   They all will have the same kinetic energy on impact.

Question 12

A worker pushes a sled with a force of 37 N over a level distance of 5.0 m.If a frictional force of 21 N acts on the wheelbarrow in a direction opposite to that of the worker,what net work is done on the wheelbarrow?

Accepted Answer

A)   290 J
B)   185 J
C)   105 J
D)   80 J
E)   ​3.2 J

Question 13

A girl and her bicycle have a total mass of 42 kg.At the top of the hill her speed is 5.0 m/s.The hill is 10 m high and 100 m long.If the force of friction as she rides down the hill is 25 N,what is her speed at the bottom?

Accepted Answer

A)   5.0 m/s
B)   12.1 m/s
C)   10.1 m/s
D)   46.3 m/s
E)   ​She stops before she reaches the bottom.

Question 14

A parachutist of mass 52.0 kg jumps out of an airplane at a height of 1 080 m.The parachute deploys,and she lands on the ground with a speed of 6.0 m /s.How much energy was lost to air friction during this jump?

Accepted Answer

A)   550 000 J
B)   191 000 J
C)   548 000 J
D)   549 000 J
E)   ​559 000 J

Question 15

A 1.00-kg ball has zero potential and kinetic energy.Maria drops the ball into a 10.00-m-deep well.After the ball comes to a stop in the mud,the sum of its potential and kinetic energy is:

Accepted Answer

A)   zero.
B)   98 J.
C)   −98 J.
D)   196 J.
E)   ​- 196 J.

Question 16

I drop a 65-g golf ball from 3.0 m high.It rebounds to 1.0 m.How much energy is lost?

Accepted Answer

A)   1.27 J
B)   12.74 J
C)   1.32 J
D)   1.22 J
E)   ​0

Question 17

Which of the following is that form of energy associated with an object's motion?

Accepted Answer

A)   potential
B)   thermal
C)   bio-chemical
D)   kinetic

Question 18

The unit of work,joule,is dimensionally the same as:

Accepted Answer

A)   newton/second.
B)   newton/kilogram.
C)   newton-second.
D)   newton-meter.

Question 19

Preston pushes a wheelbarrow weighing 490 N to the top of a 45.0-m ramp,inclined at 20.0° with the horizontal,and leaves it.Tamara accidentally bumps the wheelbarrow.It slides back down the ramp,during which an 80.0-N frictional force acts on it over the 45.0 m.What is the wheelbarrow's kinetic energy at the bottom at of the ramp? (g = 9.8 m/s2)

Accepted Answer

A)   3,942 J
B)   17,120 J
C)   11,142 J
D)   7,542 J
E)   ​1,231 J

Question 20

By how much is the energy stored in a Hooke's law spring increased when its stretch is increased from 6.00 cm to 15.00 cm?

Accepted Answer

A)   325%
B)   425%
C)   525%
D)   625%
E)   ​The correct answer is not given.

Exam 5: Energy

A pile driver drives a post into the ground.The mass of the pile driver is 2,700 kg and it is dropped through a height of 8.0 m on each stroke.If the resisting force of the ground is 3.0 × 10⁶ N,how far is the post driven in on each stroke?