Question

A Sports Car moving with a velocity of 162 Km/ h will come to rest in 5 sec
after applying the brakes. Find out the distance covered by the car before it comes to rest.PLZ ANSWER CORRECT

Answer 1

Answer: 112.5m

Explanation:Initial velocity,

u= 162 km/hr = 162×(10/36) m/s = 45 m/s

final velocity , v = 0

time taken =5 sec

S = ut + 1/2 at²   or   v²= u²+ 2aS

unknown quantity, a= ?

v= u+ at

v= u+ (-a)t ⇒ 0= 45-a×5

a=45÷5= 9 m/s²

S= ut + 1/2 at² ⇒ S= 45×5-1/2×9×5²

=225-(225/2)

=225(1-1/2)= 112.5m

OR

v²= u² + 2aS⇒ 0= 45×45-2×9S

S=45×45÷(2×9)

=45×5/2S

⇒S = 112.5 m