Question

On seeing a board of speed limit, a car decreases its speed from 90 km/h to 72 km/h at constant acceleration in 4 s. The acceleration of the car is​

Answer 1

Given,

Initial velocity of car = u = 90 km/h = 90*5/18 m/s = 25 m/s

Final velocity of car = v = 72 km/h = 72*5/18 m/s = 20 m/s

time taken = 4s

acceleration

= v-u/t

= 25-20/4

= 5/4 m/s

= 5/4 * 18/5 km/h

= 90/20 km/h

= 9/2 km/h

Answer 2

Answer:

acceleration = -1. 25 m/s²

Explanation:

INITIAL VELOCITY(u) = 90km/h= 90 ×5/18= 25 m/s

Final Velocity (v) = 72km/h = 72 × 5/18 =20 m/s

acceleration = (v-u) / t

= (20-25) /4

= -5/4

= -1. 25 m/s²