Efficiency - Edexcel

1

Why is energy wasted when surfaces rub together in a device?

2

What makes a device inefficient?

3

A motor transfers 40% of the input energy usefully. How much of every 100 J does it waste?

4

In a hairdryer, what energy is not wasted?

5

What is the efficiency of a kettle that dissipates 90 J of energy to the surroundings when supplied with 630 J?

6

How might a toy car be made more efficient? - Higher

7

What is a good thermal conductor?

8

Which is the best insulator?

9

Why is loft insulation so effective?

10

What would make the best material for wrapping around a mug to keep a hot drink warm for as long as possible?