Question

If the speed of car is reduces from 108km/hr to 36km/hr in 4 sec calculate acceleration

Answer 1

Initial Velocity = v = 108km/h = 30m/s
Final Velocity = u = 36km/h = 10m/s
Time taken = t = 4s

From first equation of motion
v = u + at
10 = 30 + a(4)
-20 = 4a
-5 m/s² = a

So acceleration is -5m/s²

Answer 2

Answer:

-5 m/s²

Step-by-step explanation:

Time taken = 4 secs

Initial velocity of car (u) = 108 km/hr

Final velocity (v) = 36 km/hr

As the initial velocity and final velocity of the car is given in kilometre per hour, we need to convert it into metre per second.

⇒ u = 108 km/hr = 30 m/s

⇒ v = 36 km/hr = 10 m/s

Now, we know that ;

Acceleration is defined as rate of change of velocity per unit time.

Acceleration = $\frac{\text{(Final - initial ) velocity}}{\text{Time \: Taken}}$

Acceleration = $\frac{10 - 30}{4}$

Acceleration = $\frac{-20}{4}$

Acceleration = - 5 m/s²

Hence, the acceleration acquired by car is - 5 m/s²