Storing of energy

Question 1

When you eat food energy is added to your bodys _____ store
Your body then transfers this energy to your ____ store when you need it to keep warm or your _____ store to move about.

Answer 1

When you eat food energy is added to your bodys chemical store
Your body then transfers this energy to your thermal store when you need it to keep warm or your kinetic store to move about.

Question 2

whenever energy is transferred from one store to another, ___ is being done

Answer 2

Work is being done

Question 3

______ work is involves using a force to move an object

Answer 3

Mechanical work

Question 4

______ work involves a current transferring energy

Answer 4

Electrical work

Question 5

A rope is attached to a dog and a sledge,

when the dog moves, the sledge is being moved too by the force of the dog, this is an example of _____ work

Answer 5

Mechanical work

Question 6

Explain the different energy transfers taking place between different stores while work is being done when…
A dog is pulling a sledge, attached to the dog is a rope, attached to theother side of the rope is the sledge.

Answer 6

The chemical energy stored in the dog transfers to the kinetic energy store in the moving sledge. This then transfers to the thermal energy store in the ground (caused by friction).

Question 7

work done means:

Answer 7

energy transfer is taking place between different stores

Question 8

the equation for work done is:

Answer 8

Work done(J) = Force(N) x Distance(m)

Question 9

In a scrum, a rugby team pushes the other team backwards 5 m using a force of 1,000 N. Calculate the work done moving the other team

Answer 9

Work done(J) = Force(N) x Distance(m)
Work done(J) = 1000N x 5m 
Work done = 5000J (or 5kJ)

Question 10

A car travels at a speed of 20m/s.
The driver applies the brakes and the car comes to a stop. Explain the different energy transfers taking place between the different stores while work is being done .

Answer 10

A car that is moving has a kinetic energy store .
When the driver presses on the brakes, the brakes press against the wheel.
This creates friction between the brake and the wheel.
At this point the kinetic energy store of the car is transferred to the thermal energy store in the brakes.
So the temperature of the brakes increases and the car slows down and stops.

Question 11

During the braking of a car, a force of 2000N is applied to the brakes of the car. The car takes 20M to come to a stop. Calculate the work done.

Answer 11

Work done(J) = Force(N) x Distance(m)
Work done(J) = 2000N x 20m 
Work done = 40 000J