Work, Energy & Power
Definitions: Work, Energy & Power
- One exam question, the mark-scheme answer, and the exact phrases that score (highlighted, then listed below in the same colour).
Exam question
Define the work done by a force.
Model answer
Work done is the product of the force and the displacement in the direction of the force.
Marking points
1 mark each- 1product of the force and the displacement in the direction of the force(1)
Exam question
Define the joule.
Model answer
One joule is the work done when a force of 1 N moves 1 m in the direction of the force.
Marking points
1 mark each- 1work done when a force of 1 N moves 1 m in the direction of the force(1)
Exam question
Define power.
Model answer
Power is the rate of doing work.
Marking points
1 mark each- 1rate of doing work(1)
Exam question
State the principle of conservation of energy.
Model answer
The total energy of a closed system is constant: energy can be transferred between forms but is not created or destroyed.
Marking points
1 mark each- 1total energy of a closed system is constant(1)
- 2not created or destroyed(1)
Exam question
Define efficiency.
Model answer
Efficiency = useful output energy ÷ total input energy.
Marking points
1 mark each- 1useful output energy ÷ total input energy(1)