Edexcel GCSE Physics 1PH0
Key Concepts of Physics
Motion and Forces
Conservation of Energy
Waves
Light and the Electromagnetic Spectrum
Radioactivity
Astronomy
Energy – Forces Doing Work
Forces and Their Effects
Electricity and Circuits
Static Electricity
Magnetism and the Motor Effect
Electromagnetic Induction
Particle Model
Forces and Matter
Motion and Forces
Braking distance, speed and work done
- 3 things to know
- Paper 1
Overview
How stopping distance grows with speed, thinking distance estimates, the work done equation, and braking distance found from the kinetic energy a braking force must remove.
What you need to know
Answer each one before you reveal it.
Estimate the thinking distance for a car travelling at 20 m/s if the driver's reaction time is 0.7 s.
Estimate the thinking distance for a car travelling at 30 m/s if the driver's reaction time is 0.8 s.
Questions from this subtopic
Each one with the model answer underneath.
- 1
Describe how the stopping distance of a car changes as its speed increases.
Model answer
The stopping distance increases, and it grows much faster than the speed itself does.
- 2
A car needs about 23 m to stop from 13 m/s. Estimate whether the stopping distance from 26 m/s is more or less than double this, and give a reason.
Model answer
More than double, because the braking part of the distance grows with the square of the speed.
- 3
Estimate the thinking distance for a car travelling at 20 m/s if the driver's reaction time is 0.7 s.
Model answer
20 × 0.7 = 14 m.
- 4
Estimate the thinking distance for a car travelling at 30 m/s if the driver's reaction time is 0.8 s.
Model answer
30 × 0.8 = 24 m.
- 5
A typical car stops from 13 m/s in about 23 m. Estimate the stopping distance from 31 m/s.
Model answer
It is roughly 100 m, about four times as far, because the braking distance grows with speed squared.
- 6
Explain why a lower speed limit outside a school reduces the risk of a serious injury.
Model answer
A lower speed gives a much shorter stopping distance and smaller forces in any impact that does occur.
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