4.5 Energy, work and power

Understand the concept of the work done by a force, and calculate the work done by a constant force when its point of application undergoes a displacement not necessarily parallel to the force.

W = Fd cos θ. Use of the scalar product is not required.

Taught in: Work done by a force: W = Fd cos θ · 3 questions

Understand the concepts of gravitational potential energy and kinetic energy, and use appropriate formulae.

Taught in: Gravitational potential energy and kinetic energy · 3 questions

Understand and use the relationship between the change in energy of a system and the work done by the external forces, and use the principle of conservation of energy in appropriate cases.

Includes cases where the motion may not be linear (e.g. a child on a smooth curved 'slide'), where only overall energy changes need to be considered.

Taught in: Work-energy principle and conservation of mechanical energy · 3 questions

Use the definition of power as the rate at which a force does work, and use the relationship between power, force and velocity for a force acting in the direction of motion.

Includes calculating (average) power as work done ÷ time taken, and P = Fv.

Taught in: Power: how fast work is done · 4 questions

Solve problems involving, for example, the instantaneous acceleration of a car moving on a hill against a resistance.

Taught in: Car on a hill: power, force and acceleration · 6 questions