Bennett Mechanical Test Bennett Mechanical Work and Energy Questions and Answers 1 — Questions and Answers
Question 1: A 20 N force pushes a box 5 meters in the direction of the force. How much work is done?
- 100 J (Correct answer)
- 25 J
- 4 J
- 200 J
Correct answer: 100 J
Work equals force multiplied by distance (W = F × d = 20 × 5 = 100 J).
Question 2: Which unit is used to measure energy in the SI system?
- Watt
- Newton
- Joule (Correct answer)
- Pascal
Correct answer: Joule
The joule (J) is the SI unit of energy, equal to one newton-meter.
Question 3: A spring with a spring constant of 200 N/m is compressed by 0.1 m. What is the elastic potential energy stored?
- 2 J
- 1 J (Correct answer)
- 0.5 J
- 20 J
Correct answer: 1 J
Elastic PE = ½kx² = ½ × 200 × (0.1)² = 1 J.
Question 4: A 5 kg object is lifted to a height of 10 m. What is its gravitational potential energy? (g = 10 m/s²)
- 50 J
- 500 J (Correct answer)
- 5000 J
- 100 J
Correct answer: 500 J
Gravitational PE = mgh = 5 × 10 × 10 = 500 J.
Question 5: A machine is 80% efficient and receives 500 J of input energy. How much useful output energy does it deliver?
- 400 J (Correct answer)
- 420 J
- 350 J
- 500 J
Correct answer: 400 J
Useful output = efficiency × input = 0.80 × 500 = 400 J.
Question 6: Power is defined as which of the following?
- Force multiplied by distance
- Mass multiplied by velocity
- Work done per unit time (Correct answer)
- Energy multiplied by time
Correct answer: Work done per unit time
Power is the rate at which work is done, calculated as work divided by time (P = W/t).
Bennett Mechanical Test Bennett Mechanical Work and Energy Questions and Answers 1
A 20 N force pushes a box 5 meters in the direction of the force.
How much work is done?