Chapter 1.8 - Wd, pe and ke.

Question 1

Define work done.

Answer 1

‘The product of a force and distance moved in the direction of the force’.

Question 2

Define power.

Answer 2

‘The rate of doing work, P = W.d / t’.

Question 3

Define efficiency.

Answer 3

‘The fraction of input energy that does work, eff = Eout / Ein’.

Question 4

Define the principle of conservation of energy.

Answer 4

‘Energy cannot be created or destroyed, merely transferred from one form to another’.

Question 5

Define kinetic energy.

Answer 5

‘The product of half the mass and the square of the velocity, k.e. = ½ m v²’.

Question 6

Define potential energy.

Answer 6

‘The product of mass, gravitational field strength and height, gpe = mgh’.

Question 7

Sketch a graph to illustrate how potential energy varies with time for an object dropped from a height.

Answer 7

Question 8

Sketch a graph to illustrate how the kinetic energy of an object varies with time as it is dropped from a datum point.

Answer 8

Question 9

State the equation which links the power of an object to the velocity it is travelling at.

Answer 9

P = F x v