Question

a moving car weighing 1200 kilogram is stopped by applying brakes which produce negative acceleration of 9 metre per second and it covers 50m before coming to rest calculate the amount and type of work done after application of brake?

Answer 1

Answer:

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Explanation:

A car of mass m=1200kg moving initially at u=90m/s

=90×

18

5

=25m/s

let the braking force be given as,

f=−3600t [as f various linearly with time]

The braking force causes retardation,which given by :-

a=

m

f

=

1200

−3600t

=−3t

as, a=

dt

dv

=−3t ⇒∫

u

v

dv=∫

0

t

−3dt

=v−u=

2

3t

2

As u=25m/s , we get:-

v=

2

−3t

2

+25

when car comes to halt v=0 so:-

25=

2

3t

2

⇒t=

3

50

s