Question

find the initial velocity of a car which is stopped in 10 sec. by applying brakes. The retardation due to brakes is 2.5 m/s^2 ........​

Answer 1

$\huge\boxed{\fcolorbox{blue}{orange}{HELLO\:MATE}}$

GIVEN:

→Retardation if the car is $2.5ms^{-2}$(a)

→Time of retardation is 10s(t)

→Final velocity of the car is 0m/s(v)

(since the car is stopped using brakes)

TO FIND:

→The initial velocity of the car. (u)

SOLUTION:

By the first equation of motion we know that,

$\large\green{\boxed{ v= u+at}}$

The symbols value are mentioned above in brackets.

On substituting the values, we have;

=>$v = u+at$

=>$0m/s = u + -2. 5ms^{-2}×10$

(Here a is -ve since the body is retarding)

=>$0 m/s= u - 25m/s$

=>$u =(0+25) ms^{-1}$

=>$u = 25ms^{-1}$

Therefore initial velocity of the car is 10m/s .

$\huge\orange{\boxed{Answer:25ms^{-1}}}$