WTMA Energy, Work, and Power 2

Question 1

A 200-pound crate is pushed 15 feet along a level floor. How much work is done against gravity?

Accepted Answer

0 ft-lb

Answer

No work is done against gravity when an object moves horizontally, since gravity acts vertically.

Question 2

Which of the following best describes potential energy?

Accepted Answer

Stored energy due to position or condition

Answer

Potential energy is stored energy that an object has due to its position, shape, or condition.

Question 3

How much work is done when a 300 lb engine block is lifted 4 feet onto a workbench?

Accepted Answer

1,200 ft-lb

Answer

Work = Force × Distance = 300 lb × 4 ft = 1,200 ft-lb.

Question 4

A motor lifts a 500 lb load 10 feet in 5 seconds. What is the power output?

Accepted Answer

1,000 ft-lb/s

Answer

Power = (Force × Distance) / Time = (500 × 10) / 5 = 1,000 ft-lb/s.

Question 5

Two workers each move identical boxes up the same flight of stairs. Worker A takes 10 seconds; Worker B takes 20 seconds. Which statement is true?

Accepted Answer

Both do the same work but A uses more power

Answer

Work depends only on force and distance, so both do the same work, but Worker A uses more power because she completes it in less time.

WTMA - Wiesen Test of Mechanical Aptitude Practice Test