Flashcards - 1.1 Energy Changes in a System - AQA Physics GCSE

What is the equation for kinetic energy?

The equation for kinetic energy is ½ m v², where m is mass in kg and v is velocity in m/s.

What is the equation for elastic potential energy?

The equation for elastic potential energy is ½ k x², where k is the spring constant in N/m and x is the extension in m.

What is the equation for gravitational potential energy?

The equation for gravitational potential energy is mgh, where m is mass in kg, g is gravitational field strength in N/kg, and h is height in m.

Define 'Specific Heat Capacity' of a substance.

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

What are the units for Specific Heat Capacity?

The units for Specific Heat Capacity are J/°C/kg.

What is the definition of 'Power'?

Power is the rate at which energy is transferred or the rate at which work is done.

State two equations for power and their SI units.

1. Power = energy transferred/time (Energy in J, Time in s); 2. Power = work done/time (Work Done in J, Time in s).

What is the unit of power?

The unit of power is Watt (W).

When two motors lift the same mass through the same height, which dissipates the most power if Motor A does it in half the time of Motor B?

Motor A dissipates the most power.

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

When thrown upwards, KE is converted to GPE; at the peak, GPE is max and KE is zero; during descent, GPE is converted back to KE.

Describe the energy transfers for a bungee jumper.

During free fall, GPE is converted to KE; as the cord tightens, KE is converted to elastic potential energy (EPE); at the lowest point, initial GPE equals stored EPE.

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

Kinetic energy decreases since it is converted to elastic potential energy, resulting in a decrease in velocity as KE is proportional to velocity squared.

Give examples of chemical energy stores.

Examples of chemical energy stores include food, fuel (wood, coal, petrol), and batteries.

State 4 different stores of energy.

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