Topic 1 - Energy

Question 1

Kinetic energy equation

Answer 1

Kinetic Energy (J) = 1/2 • mass(kg) • speed(m/s)^2

Question 2

Gravitational Potential Energy equation

Answer 2

GPE = mass(kg) • gravitational field strength(N/kg) • height(m)

Question 3

Power equations

Answer 3

1. Power = work done : time taken(s)
2. Power = energy transferred (J) : time taken(s)

Question 4

Efficiency equations

Answer 4

1. Efficiency= useful energy output : total energy input
2. Efficiency= useful power output : total power output

Question 5

What is a system?

Answer 5

A single/group of objects you’re interested in.

Question 6

Describe the energy transfers that occur when a car collides with a stationary object

Answer 6

• Car begins with kinetic energy as it’s moving.
• When the car collides, some of the kinetic energy is transferred to elastic potential and thermal energy of the object and car’s body
• Sound energy transferred from the kinetic energy is transferred to the surroundings.

Question 7

If energy is transferred to a object’s kinetic energy store, what happens to its speed?

Answer 7

It increases.

Question 8

What kind of energy store is energy transferred to when you compress a spring?

Answer 8

Elastic potential.

Question 9

What is the definition of specific heat capacity of a material?

Answer 9

The amount of energy needed to raise the temperature of 1 kg of a substance by 1°C.

Question 10

Suggest why a material with a high specific heat capacity is better suited for use in a heating system than a material with a low specific heat capacity.

Answer 10

A material with a high specific heat capacity can transfer loads of energy when they cool down again after being heated, so they can ‘store’ a lot more than a material with low specific heat capacity.

Question 11

Practical:
Describe an experiment to find the specific heat capacity of a material.

Answer 11

1. You’ll need a block of the material with 2 holes in it (for the heater and thermometer to go into).
2. Measure the mass of the block, then wrap it in an insulating layer to prevent energy from transferring from the block to the surroundings.
3. Insert the thermometer and heater into the holes of the material.
4. Measure the initial temperature of the block using the thermometer and set the potential difference of the power supply to be 10V. Turn on the power supply and start a stopwatch.
5. As the block heats up, use the thermometer to measure its temperature every minute.
6. Once you’ve collected enough readings, turn off the power supply.
7. Use the calculation (∆E=mc∆°C) to find the material’s specific heat capacity.

Question 12

True or False? Energy can be destroyed

Answer 12

False

Question 13

How much energy is transferred each second to a 50 W device?

Answer 13

50 J

Question 14

True or False? A high thermal conductivity means there is a high rate of energy transfer.

Answer 14

True

Question 15

How can you reduce unwanted energy transfers in a machine with moving components?

Answer 15

Lubrication (reduces friction)

Question 16

Give 4 ways to prevent unwanted energy transfers in a home.

Answer 16

• Cavity walls
• double-glazed windows
• Draught excluders
• Loft insulation

Question 17

True or False? Thicker walls make a house cool down quicker

Answer 17

False

Question 18

Practical:
Describe an experiment you could do to investigate ways of reducing unwanted energy transfers.

Answer 18

1. Boil water in a kettle. Pour some water into a sealable container.
2. Use a thermometer to measure the initial temperature of the water.
3. Seal the container and leave it for 5 minutes using a stopwatch.
4. Remove the lid and measure the final temperature of the water using a thermometer.
5. Pour away the water and allow the container to cool to room temperature.
6. Repeat this experiment but wrap the container each time with a different material.

Question 19

What is the difference between a renewable and non-renewable energy resource?

Answer 19

Renewable energy resources will never run out(they are infinite), non-renewable energy resources do(they are finite).

Question 20

Give an example of how a renewable energy resource is used in everyday life.

Answer 20

Vehicles that run on pure biofuel as energy.

Question 21

Explain why solar power is considered to be a fairly reliable energy resource.

Answer 21

It doesn’t cause much environmental damage and is very inexpensive after paying the initial costs for setting up.

Question 22

Give one environmental impact of using wave power to generate electricity.

Answer 22

Disturbs the seabed and the habitats of marine animals.

Question 23

Describe how you can reduce the acid rain caused by burning coal and oil.

Answer 23

Produce energy using renewable sources of energy.

Question 24

Give one environmental benefit of using nuclear power.

Answer 24

Releases no polluting gases.