Question

A car weighing 1000kg and travelling at 30m/s syops at a distance of 50m deaccelerating uniformly . what is the force exerted on it by the brakes ? what is the work done by the brakes??​

Answer 1

Answer:acceleration=9m/s^2

Work done= 450000J

Explanation:

a) 2as=v^2-u/^2

where ‘v’ is final velocity

‘u’ is initial velocity

‘a’ is acceleration

‘s’ is displacement

Using this eq

2(a)(50)=0^2-30^2

100a=0-900

a=-9ms^-2

So deceleration is 9(not -9)

b) W=F.d. Eq1

where ‘F’ is force

‘d’ is diplacement

Since

F=ma Eq2

‘m’ is mass

‘a’ is acceleration

Using eq 2

F=1000x9

= 9000N

Using eq 1

W=9000x50

=450000J