GCSE Physics

Work Done & KE

danger of skidding!

From our understanding of work done and kinetic energy, we can write:

F × d = ½ × m × v²

This is a complicated formula, and is normally given for you in the exam - check with your specific syllabus! Usually you just need to know how to use it...

e.g. According to the Highway Code, a car travelling at 31·1 m/s has a braking distance of 75 m. If a car's mass is 1000 kg, what braking force was applied?

F d = ½ m v²
F × 75 = ½ × 1000 × 31·1²
F = 6,448 N = 6·5 kN

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