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Work, Power And Energy
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05/11/2021 10:40 am
Topic starter
On a level road, a scooterist applies brakes to slow down from a speed of 10 m/s to 5 m/s. If the mass of the scooterist and the scooter be 150kg, calculate the work done by the brakes.
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05/11/2021 10:43 am
Mass of scooter + scooterist = 150 kg
Initial velocity, u = 10 m/s
Final velocity, v = 5 m/s
Retardation = a
Distance travelled = s
Using third equation of motion,
v2 – u2 = 2as
as = \(\frac{-75}{2}\)
Work done, W = Fs
W = mas
W = -5625 J
Negative sign is used to show that force applied by the brakes is acting opposite direction of motion.