Physics - paper1

Define the ‘Specific Heat Capacity’ of a substance.

The amount of energy needed to raise the temperature of 1 kilogram of a substance by 1 degree Celsius.

State the units for Specific Heat Capacity.

J/°C/kg

What is the definition of ‘Power’?

The rate at which energy is transferred

What is the unit of power?

Watt (W)

Two motors lift the same mass through the same height. Motor A does this in half the time of Motor B. Which dissipates the most power?

Motor A. The energy transferred is the same but the time taken is less (P=E/t).

Describe the energy changes involved when a ball is thrown upwards and then returns to its starting position. Ignore air resistance.

Upwards: KE is converted to GPE ● Peak: Maximum GPE, zero KE ● Downwards: GPE is converted to KE

Describe the energy transfers for a bungee jumper.

When falling, the GPE is converted to KE of jumper ● As the cord tightens, KE is converted and stored as Elastic Potential Energy (EPE) ● At lowest point, the jumper’s initial GPE equals the EPE stored in the cord

Explain why a bungee jumper slows down once the cord begins to stretch.

Kinetic energy decreases since it is converted to elastic potential energy ● Since KE is proportional to (velocity)², as KE decreases, so does velocity.

Give examples of chemical energy stores.

● Food ● Fuel (eg. wood, coal, petrol) ● Batteries

State 4 different stores of energy.

1. Kinetic Energy 2. Gravitational Potential Energy 3. Elastic Potential Energy 4. Chemical Energy