HKDSE (Hong Kong) · Physics
Energy
10 practice questions, each with the answer and an explanation.
Practise Energy now
Random questions from this topic, one at a time. You see the answer and the explanation straight after each one.
All 10 questions
- A machine takes in 200 J of energy and gives out 160 J of useful energy. What is its efficiency?
- A machine takes in 500 J of energy and gives out 200 J of useful energy. What is its efficiency?
- A machine takes in 400 J of energy and gives out 200 J of useful energy. What is its efficiency?
- A machine takes in 800 J of energy and gives out 640 J of useful energy. What is its efficiency?
- A constant force of 50 N pushes a box 2 m along a floor in the direction of the force. How much work is done?
- A force of 20 N acts at 60° to the horizontal on a box, moving it 3 m horizontally. How much work does the force do? ()
- A force of 120 N acts at 60° to the horizontal on a box, moving it 2 m horizontally. How much work does the force do? ()
- A constant force of 80 N pushes a box 3 m along a floor in the direction of the force. How much work is done?
- A constant force of 50 N pushes a box 10 m along a floor in the direction of the force. How much work is done?
- Which of these energy sources is renewable?