**Unit 5: Work, Energy and
Power**

**Problem Set B**

The following selection of problems are sample problems. Individual student problem sets will vary since numerical information is randomly-generated.

**Directions:**

For the following problems:

- Compute the unknown quantity and enter the answer in the blank.
- Use 9.8 m/s/s for the numerical value of g for situations upon Earth
- Do not round any computed numbers until the last calculation.
- Enter your answers accurate to the second decimal place (unless told otherwise).

**Problem 1: **

A car is moving across a level highway with a kinetic energy of 120922 Joules. The brakes are applied and the wheels become locked as the 841-kg car slows to a stop over 5.31 seconds. Determine the work (in Joules) done upon the car. If the value is negative, then enter your answer as a negative number.

**Problem 2: **

A skier is moving along a plateau of a ski slope with a kinetic energy of 6209 Joules and a potential energy of 10418 Joules (relative to the bottom of the slope). If the skier has a kinetic energy of 22418 Joules at the bottom of the slope, then what quantity of work (in Joules) was done upon the skier by use of the poles? If the value is negative, then enter your answer as a negative number.

**Problem 3: **

A volleyball approaches a GBS spiker with a kinetic energy of .441 Joules and a potential energy of 1.209 Joules. If the ball has a kinetic energy of 4.209 Joules as it strikes the ground, then what quantity of work (in Joules) does the spiker do upon the ball? If the value is negative, then enter your answer as a negative number.

**Problem 4: **

A 160-gram baseball is moving with a kinetic energy of 39.7 Joules and a potential energy of 47.6 Joules at one location in its trajectory. If the effect of air resistance on the baseball can be ignored, then what is its kinetic energy (in Joules) the instant prior to striking the ground?

**Problem 5: **

A bowling ball is attached by a 2.55-meter cable to the ceiling. It has 10.5 Joules of potential energy when held at a height of 4 feet above the ground. It is released from rest allowed to swing as a pendulum. Determine its kinetic energy (in Joules) when it is at a height of 1 foot above the ground.

**Problem 6: **

Pete Zaria applies a rightward force of 1.2 Newtons over a distance of .541 meters to set a 631 gram root beer mug from rest into motion along a level countertop. Determine the kinetic energy (in Joules) of the root beer mug after Pete is done pushing it. Enter your answer, accurate to the third decimal place; avoid rounding until the end.

**Problem 7: **

Esteemed Chinese ski jumper, Li Ping Phar, leaves the jump ramp with a kinetic energy of 16046 Joules and a potential energy (relative to the bottom of the ski hill) of 12836 Joules. She encounters -2052 Joules of work due to air resistance during her flight through the air. Determine her kinetic energy (in Joules) the instant prior to striking the ground at the bottom of the hill.

**Problem 8: **

Mr. Henderson's Fiat is in the auto shop. A machine does 12418 Joules of work to hoist the car up to a height of 1.57 meters. Determine the mass (in kg) of the Fiat.

**Problem 9: **

A 160-gram baseball is moving with a kinetic energy of 39.7 Joules and a potential energy of 47.6 Joules at one location in its trajectory. If the effect of air resistance on the baseball can be ignored, then what is its speed (in m/s) the instant prior to striking the ground?

**Problem 10: **

A 631-kg roller coaster car is lifted to a height of 47 meters above the ground where it begins its descent from an initial rest position. If -10523 Joules of work are done on the car as it descends the first hill to ground level, then what is its kinetic energy (in Joules) at the bottom.

**Problem 11: **

A 2.2 kg physics cart starts from rest at the top of a .62-meter high incline. Determine the kinetic energy (in Joules) of the cart at the bottom of the hill.

**Problem 12: **

A 320.9 gram ball is moving along the ground with a speed of 2.1 m/s. It approaches a hill inclined at 16 degrees to the horizontal. What potential energy (in Joules) will the ball have when it reaches the peak of its path up the incline? (Ignore any effects of rotation or friction.) Enter your answer accurate to the third decimal place.

**Problem 13: **

Esteemed Chinese ski jumper, Li Ping Phar, leaves the jump ramp with a kinetic energy of 16046 Joules and a potential energy (relative to the bottom of the ski hill) of 12836 Joules. She encounters -2052 Joules of work due to air resistance during her flight through the air. Determine the speed (in m/s) of her 49.2-kg body the instant prior to striking the ground at the bottom of the hill.

**Problem 14: **

A 431-kg roller coaster car is moving with a speed of 15 m/s at the top of a 16.4-meter high loop. What is the kinetic energy (in Joules) of the car at the bottom of the loop?

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