P1.3 Energy And Work

Question 1

If a kettle uses 150J to heat water and 35J to heat the surroundings what is the total energy inpit

Answer 1

185J

Question 2

What is work

Answer 2

The amount of energy transfer

Question 3

How to work out ‘work’

Answer 3

Work = Force (N) x distance (s)

Question 4

Calcukate the work done when a person applies a force of 15N to a box moving it 2 metres

Answer 4

15 (N) x 2 (s) = 30J

Question 5

Rearrange the equation to make s the subject

Answer 5

Work / force = distance

Question 6

True or false: our lifting force is greater to the weight if an object to lift it up

Answer 6

False. It is equal

Question 7

Why do brakes get really hot?

Answer 7

The friction between the break pads and wheel disc opposes the motion of the wheel, the force of friction does work on the break pads and discs.

Question 8

What are the energy transfers of a meteorite entering the earths atmosphere

Answer 8

Gravitational potential pulls the meteorite down to earth which converts to an immense kinetic energy store due to the decreasing gravitational potential. The fast moving object then opposes the atmosphere and air resistance causing friction, which transfers to a thermal energy store - the intense heat causes the meteorite to glow causing light energy