A motorcar is moving with a velocity of 108 km/h and it takes 4 s to stop after the brakes are applied. Calculate the force exerted by the brakes on the motorcar if its mass along with the passengers is 1000 kg.

NCERT Class IX
Sciences - Main Course Book

Chapter 9. Force and Laws of Motion

1

Answers

2015-05-22T02:26:20+05:30
108 km/h = 30m/s
when the car stops velocity of the car will b 0
using ' v = u - at ' ( v = final & u = initial velocity , a = deceleration, t = time)
we get a = 7.5 ms⁻² 
mass of the car = 1000kg
so force exerted by the brakes on themotorcar
= 1000 
× 7.5 = 750 N
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