Chapter 5 - Work, Energy and Power

Question 1

Define Work done, in terms of force and distance.

Answer 1

Work done is defined as the product of the force exerted on an object and the distance travelled in the direction of the force.

W = Fx
Work Done = Force x Distance
Nm = N x m

Question 2

What is the relationship between work done and energy?

Answer 2

The relationship between work done and energy:

Work Done = Energy Transferred.

Question 3

Define Energy as a quantity in terms of work.

Answer 3

Energy is defined as the capacity for doing work and it is a scalar quantity.

Question 4

Define the principle of conservation of energy.

Answer 4

The principle of conservation of energy states that the total energy of a closed system remains constant: energy can never be created or destroyed but it can be transferred.

Question 5

Define Kinetic Energy.

Answer 5

Kinetic Energy is energy associated with an object as a result of its motion.

E = 1/2 mv²
Energy = 1/2 x mass x velocity²
J = 1/2 x kg x (ms⁻¹)²

Question 6

Define gravitational potential energy.

Answer 6

Gravitational potential energy is the capacity for doing work as a result of an object’s position in a gravitational field.

GPE = mgh
Gravitational potential energy = mass x gravity x height
J = kg x ms⁻² x m

Question 7

Define a power in mechanics, using work done.

Answer 7

Power is defined as the rate of work done.

P = W ÷t
Power = Work Done ÷time
W = J ÷s

Question 8

Define a power in mechanics, using velocity.

Answer 8

Power is defined as the product of the force and the velocity of an object.

P = Fv
Power = Force x velocity
W = N x ms⁻¹