On a level road, a scooterist applies brakes to slow down from a speed

1.	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.
Answer» 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 = -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.

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.

Answer»

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 = -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.