Question

A bus decreases its speed from 144 km/h to 72 km/ h in 5 s. The acceleration of the bus will be​

Answer 1

Given :-

Initial velocity = 144 km/h

Final velocity = 72 km/h

Time = 5 sec

To Find :-

Acceleration

Solution :-

1 km/h = 5/18 m/s

144 km/h = 144 × 5/18 = 40 m/s

72 km/h = 72 × 5/18 = 20 m/s

Acceleration = v - u/t

a = 20 - 40/5

a = -20/5

a = -4 m/s²

Hence

Acceleration is -4 m/s²

Answer 2

Answer:-

• Initial velocity=u=144km/h=40m/s
• Final velocity=v=72km/h=20m/s
• Time=t=5s

We know that.

$\boxed{\sf Acceleration=\dfrac{v-u}{t}}$

$\\ \sf\longmapsto Acceleration=\dfrac{20-40}{5}$

• It retards here

$\\ \sf\longmapsto Retardation =\dfrac{-20}{5}$

$\\ \sf\longmapsto Retardation=-4m/s^2$