Physics: Forces, Motion and Energy Resources
Forces, motion and energy resources, at 13+ Physics, extends the forces and energy ideas from Forces and Energy into two further areas.
Before you start
Make sure you're comfortable with these topics first:
Method
- For speed questions, write down speed = distance / time before substituting numbers, and check your units match (e.g. distance in metres and time in seconds gives speed in m/s).
- On a distance-time graph, identify flat (horizontal) sections as the object being stationary, and read the gradient (steepness) of a sloped section as the object's speed, a steeper line meaning a faster speed.
- For acceleration questions, write down acceleration = change in velocity / time taken, find the change in velocity first (final velocity minus initial velocity), then divide by the time this change took.
- Remember a negative value for acceleration means the object is slowing down (decelerating), not speeding up.
- For energy resource questions, sort each named resource into renewable (will not run out on a human timescale, e.g. wind, solar, hydroelectric, tidal) or non-renewable (finite, e.g. coal, oil, natural gas, nuclear fuel) before answering.
- Learn the general pattern most power stations share: a fuel is burned or reacted to boil water into steam, the steam turns a turbine, and the turbine turns a generator to produce electricity; then learn which renewable resources skip the boiling step and turn the turbine directly (e.g. wind or moving water).
- For 'evaluate' or 'compare' questions on energy resources, give one advantage AND one disadvantage of each resource named in the question, covering both environmental impact and reliability of supply.
Worked example
A cyclist travels 300 m in 25 seconds at a constant speed, then speeds up and travels a further 200 m in the next 10 seconds. (a) Calculate her speed for the first 300 m. (b) Calculate her speed for the next 200 m. (c) State which part of the journey she was travelling faster.
- For the first part, write down speed = distance / time = 300 / 25.
- Calculate: 300 / 25 = 12, so her speed for the first 300 m is 12 m/s.
- For the second part, substitute again: speed = 200 / 10.
- Calculate: 200 / 10 = 20, so her speed for the next 200 m is 20 m/s.
- Final answer: (a) 12 m/s; (b) 20 m/s; (c) she was travelling faster during the second part of the journey (20 m/s is greater than 12 m/s).
Practice questions
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Q1A runner covers 400 m in 50 seconds at a constant speed. Use speed = distance / time to calculate her speed.Show answer
Answer: 8 m/s (400 / 50 = 8).
Q2State the unit normally used for speed in physics, and name one other unit that speed could also correctly be measured in.Show answer
Answer: Metres per second (m/s) is the standard unit; speed could also correctly be measured in km/h (kilometres per hour) or mph (miles per hour).
Q3A car's velocity increases from 5 m/s to 17 m/s in 4 seconds. Use acceleration = change in velocity / time taken to calculate its acceleration.Show answer
Answer: 3 m/s^2 ((17 - 5) / 4 = 3).
Q4State whether solar power is a renewable or a non-renewable energy resource.Show answer
Answer: Renewable.
Q5Name one non-renewable energy resource used to generate electricity, other than coal.Show answer
Answer: Oil, natural gas, or nuclear fuel (any one).
Q6State one reason, other than cost, why a country might want to reduce its reliance on non-renewable energy resources such as coal and oil.Show answer
Answer: They are finite (non-renewable), so supplies will eventually run out, unlike renewable resources such as wind or solar.
Q7A wind turbine and a coal power station both generate electricity, but only one of them directly burns fuel to boil water into steam. State which one this is, and name the component that this steam turns.Show answer
Answer: The coal power station; the steam turns a turbine (which then turns a generator).
Q8A skateboarder travels at a constant speed of 4 m/s for 6 seconds. Use acceleration = change in velocity / time taken to state his acceleration during this time, and explain what an acceleration of zero means about his motion.Show answer
Answer: 0 m/s^2; an acceleration of zero means his speed is not changing, but this does not mean he is stationary, since he is still moving at a constant 4 m/s.
Exam-style questions
Written in the style of a 13+ Common Entrance exam paper, with a full mark scheme.
A bus's journey between two stops is recorded on a distance-time graph made up of two straight sections. From 0 to 20 seconds, the bus travels 100 m. From 20 to 50 seconds, it travels a further 210 m. (a) Calculate the bus's speed during the first 20 seconds. (b) Calculate the bus's speed during the next 30 seconds. (c) A pupil says the graph shows the bus decelerating between the two sections. Use your answers to (a) and (b) to say whether the pupil is correct, and explain why.
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A newly built power station can either burn natural gas or use a large hydroelectric dam to generate electricity for a town. 'Hydroelectric power is always a better choice of energy resource than natural gas.' Discuss this statement, giving points for and against, before reaching a conclusion.
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A delivery van accelerates from rest to 15 m/s in 5 seconds. (a) Use acceleration = change in velocity / time taken to calculate its acceleration. (b) The van then brakes and slows from 15 m/s to 3 m/s in 4 seconds. Calculate its acceleration during braking, and explain what the sign of your answer shows.
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Free printable worksheet
Want more practice on paper? Download the physics: forces, motion and energy resources worksheet pack - 18 pages of exam-style questions with a full mark scheme. One email opens every download in this browser for 14 days - no account, no card. Print it for personal and classroom use.
This topic is chapter 14 of 13+ Science Workbook, the whole course as one free printable PDF.
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