Question

A car starts from the rest accquire a velocity of 20km/h in 4 sec. find the acceleration of car.​

Answer 1

Answer:

u = 0km/h

v= 20km/h

t= 30/60 hr = 1/2hr

therefore, using first equation of motion

v=u+at

20=0+a(1/2)

20=a/2 => a =40km/h²

using second equation of motion

s=ut+1/2at²

s=0(1/2)+1/2(40)(1/2)²

s= 0+5 =5km

Answer 2

Answer:

1.38 m / sec²

Explanation:

Given :

Initial velocity u = 0 m / sec

Final velocity v = 20 km / hr

In term of m / sec :

v = 20 × 5 / 18  = 100 / 18 = 50 / 9 m / sec

Time t = 4 sec

We have to acceleration :

We know :

Acceleration = Change in velocity / Change in time :

i.e a = Δ v / Δ t

a = ( 50 / 9 - 0 ) / 4 m / sec²

= > a = ( 50 / 9 ) / 4 m / sec²

= > a = 50 / 36 m / sec²

= > a = 1.38 m / sec²

Hence we get required answer.