Question

An empty car moving with a certain velocity on a frictionless road can
be stopped in a distance 's'. If the passenger add 40kw of its weight and
same braking force is applied, the stopping distance for the velocity will be
1) 1.4 s
2) √1.4s
3) (1.4)^2
4) s/1.4​

Answer 1

Explanation:

Given An empty car moving with a certain velocity on a friction less road can  be stopped in a distance 's'. If the passenger add 40 % of its weight and  same braking force is applied, the stopping distance for the velocity will be

Let m be the mass of empty car then

FS = 1/2 mu^2 ---------1

Where F is the retarding force, so 40% weight is added, new mass will be

So m1 = m + (40/100) m

              = 1.4 m

Now F S1 = 1/2 m1u^2

                = 1/2 x 1.4 mu^2---------------2

From 1 and 2 we get

S1 = 1.4 S