Question

The brakes of a car can produce an acceleration of -12m/s². If a speeding car is brought to rest in 3 s, calculate the initial velocity of the car in (i) m/s (ii) km/h.​

Answer 1

$</p><p>\blue{\underline{\underline{Answer: }}}$

$</p><p>\orange{\underline{\underline{Step \: By \: Step \: Explaination }}}$

Use the following formula :

$</p><p>\huge{\green{\boxed {\boxed{V \: = \: U \: + \: AT }}}}$

V = Final Velocity of the particle

U = Initial Velocity of the particle

A = Net Acceleration

T = Time Taken

$</p><p>\red{\boxed{\underline{Here \: :}}}$

V = 0 m/s^2

A = -12 m/s^2

T = 3 seconds

$</p><p>\blue{\boxed{\boxed{\underline{\therefore { U\: = \:36 \:m/s\: = \:10 \: km/hr}}}}}$

Answer 2

36  m/s

129.6 Km/h

Explanation:

V= 0

a = -12 m/s²

v = u +at

v = 0

u = -a t

  =    - (-) 12 * 3

   = 36 m/s .

In Km /h

129.6 Km/h