Question

A bus decreases its speed from 8 km/h to 60 km/h in 5 s. Find the acceleration of the bus

Answer 1

Answer:

Explanation:

Given :-

Initial velocity of bus, u = 8 km/h = 8 × 5/18 = 2.22 m/s

Final velocity of bus, v = 60 km/h = 60 × 5/18 = 16.67 m/s

Time taken by bus, t = 5 seconds

To Find :-

Acceleration, a = ??

Formula to be used :-

1st equation of motion,

i.e v = u + at

Solution :-

Putting all the values, we get

v = u + at

⇒ 16.67 = 2.22 + a × 5

⇒ a = 16.67 - 2.22/5

⇒ a = 14.45/5

⇒ a = - 2.89 m/s²

Hence, the acceleration of the bus is - 2.89 m/s².

Negative sign of acceleration means velocity is decreasing.

Answer 2

Acceleration of bus is 2.9 m/s²

Explanation :

Here initial speed of bus is 8 km/h

⇒ 8 × (5/18) m/s

⇒ 2.22 m/s

Again final speed of bus is 60 km/h

⇒ 60 × (5/18) m/s

⇒ 16.67 m/s

Time taken (t) = 5 seconds.

We will use 1st equation of motion :

⇒ v = u + at

⇒ 16.67 = 2.22 + a × 5

⇒ 16.67 - 2.22 = 5a

⇒ 14.45 = 5a

⇒ a = 14.45/5

⇒ a = 2.9 m/s²

∴ Acceleration of bus = 2.9 m/s² .