Unit 1.4: Energy Concepts

Question 1

What is work done equal to?

Answer 1

Work done is always equal to the energy transferred.

Question 2

Equation that links with Work done

Answer 2

W=FxCosθ

Question 3

On a Force-Distance graph, what is the area under the graph equal to?

Answer 3

Work done. This is true whether the force is a constant or not

Question 4

State the conservation of energy

Answer 4

Energy cannot be created or destroyed, only transferred from one o form to another

Question 5

What is power defined as?

Answer 5

The rate of not doing work. It is also the rate of transferring energy

Question 6

What is efficiency?

Answer 6

A quantity used to describe how much useful energy a device produces as compared to the input energy. It is usually expressed as a percentage.

Question 7

State the equation for efficiency

Answer 7

Useful energy transfer/total energy transfer x 100=Efficiency(%)

Question 8

What is the work-energy theorem?

Answer 8

A force pushing an object horizontally does work on the object equal to “F x”, and in the absence of friction etc, this work translates to a gain in kinetic energy.

Question 9

How is the equation for work-theorem obtained?

Answer 9

The kinematic equation V²=u²+2ax
If we re-arrange for ‘a’ and substite for ‘a’ in F=ma, then we get the equation
F x = ½ mv2 - ½ mu2