Key Stage 3 Science Book 3 Assessments
Exploring Contact and Non-Contact Forces (Purple level)
Answers
1. Complete this sentence about energy when a change happens: The quantity of energy stored before
the change is __ [1 mark]
b)
Difficulty level: moderate
Skill level: knowledge
2. Which statement about how an image is formed in the human eye is correct? [1 mark]
a)
Difficulty level: difficult
Skill level: knowledge
3. Which statement about a hot metal pan cooling down is false? [1 mark]
d)
Difficulty level: difficult
Skill level: application
4. Match the descriptions to the types of wave. [1 mark]
A wave which moves up and down
Transverse
A water wave
Transverse
A sound wave
Longitudinal
A wave which moves forwards and
backwards
Longitudinal
5. Which two statements about red and blue light are correct? [1 mark]
a), d)
Difficulty level: moderate
Skill level: knowledge
6. A beam of light from a torch is shone through a glass window. Which two statements about it are
correct?
[1 mark]
Difficulty level: difficult
Skill level: application
© HarperCollinsPublishers 2014
Key Stage 3 Science Book 3 Assessments
7. Using the idea of particles, describe how thermal conduction takes place in a solid. [2 marks]
(the answer should contain two of the following)
1) The hotter the object the faster the particles vibrate
2) Energy is transferred as the particles collide
3) Thermal equilibrium is reached when all the particles vibrate at the same speed
Difficulty level: moderate
Skill level: knowledge
8. Describe what is meant by ‘the rate of energy transfer’. [2 marks]
(the answer should contain two of the following)
1) How quickly energy is transferred from one energy store to another
2) The rate of energy transfer is called ‘power’
3) Power equation (power equals energy transferred divided by time taken)
Difficulty level: difficult
Skill level: knowledge
9. Explain why you can see your reflection in a pond when the water is still, but not when it is choppy. [2
marks]
(the answer should contain the following)
1) Choppy water produces diffuse scattering (reflects light in different directions)
2) A smooth water surface produces specular reflection (reflects light in the same direction)
Difficulty level: difficult
Skill level: application
10. Explain why scientists say no energy is lost or used up when things happen. [2 marks]
(the answer should contain the following)
1) When things happen, energy is transferred
2) The quantity of stored energy before a change is the same as the quantity of stored energy after the
change
Difficulty level: moderate
Skill level: knowledge
11. Explain what is meant by superposition of water waves. [2 marks]
(the answer should contain the following)
1) When crests or troughs coincide, waves add together to make a bigger wave
2) When crests coincide with troughs, waves cancel each other out
Difficulty level: difficult
Skill level: knowledge
© HarperCollinsPublishers 2014
Key Stage 3 Science Book 3 Assessments
12. A household uses 800 kWh of electricity at 12p per kWh, and 1000 kWh of gas at 5p per kWh.
Explain what you think their bill should be. [4 marks]
(the answer should contain the following)
1) 800 multiplied by 12 equals 9600p equals £96
2) 1000 multiplied by 5 equals 5000p equals £50
3) Total equals £146 (or correct addition of their figures)
4) Plus a standing charge
Difficulty level: application
Skill level: knowledge
13. A house is supplied with mains gas. Explain what they might use the gas for, and why scientists say
no energy is lost or used up. [4 marks]
(the answer should contain four of the following)
1) Gas used for heating and/or cooking
2) Energy transferred to the surroundings
3) Quantity of energy stored in the gas is the same as the energy now stored in the surroundings
4) Total amount of energy remains the same
5) Law of Conservation of Energy
Difficulty level: difficult
Skill level: application
14. Michael is fitting solar panels to the roof of his house:
They weren’t cheap to buy but he tells his neighbours he expects to “have got his money back in ten
years.” What does this mean? [2 marks]
(the answer should contain the following)
1) Cheaper way of producing electricity than buying it from an electricity supply company
2) After ten years the savings will have covered the cost of installation
Difficulty level: difficult
Skill level: evaluation
© HarperCollinsPublishers 2014
Key Stage 3 Science Book 3 Assessments
15. Sue and Jo are buying a new electric kettle for their flat to make tea. They find a design they like but
then find out they can buy it either with a 1000W element or a 2000W element.
Sue says “We should buy the 1000W one as it will use less electricity and be cheaper to run.”
Jo says “We should buy the 2000W one as it will boil the water quicker, so energy will have less chance
to escape and it will be more efficient.”
The sales assistant says “Both kettles are the same shape, size and material so they will be as efficient as
each other. It’s just down to how quickly you want your tea.”
Who is right, and why? [4 marks]
(the answer should contain four of the following)
1) The 1000W kettle will take longer to get a certain amount of water to boiling point.
2) It takes a certain amount of energy to get the water to boil
3) The 2000W kettle will supply the energy more quickly
4) The quicker the energy is supplied, the less chance it has to escape
5) The 1000W kettle won’t be cheaper to run – more energy will have escaped to the surroundings as it
takes longer to boil the water
6) They won’t be as efficient as each other – taking longer to heat the water means more energy lost.
Difficulty level: moderate
Skill level: evaluation
© HarperCollinsPublishers 2014