Question

a car moving along a straight highway with a speed of 72 km/h is brought to a stop within a distance of 100m.what is the retardation of the car and how does it take for the car to stop?​

Answer 1

Answer:

Here, `u=72km h^(-1) =72 xx 5/(18)`

`=20 ms^(-1)`:

`v=0, S=100 m: a=?

Acceleration, `a(v^(2)-u^(2))/(2 S) =(0-20^(2))/(2xx 100) =- 2 ms^(2)`

i.e. retardation `=- a=2 ms^(-2)` ltbtgt Time `t= (v-u)/a = (0-20)/(-2) =10 s`.