Question

A bus decreases its speed from 108 km/h to 72 km/h in 5 s. Find the acceleration of the bus.​

Answer 1

Answer:

• 2m/s² is the required answer

Explanation:

Given:-

• Initial velocity ,u = 108km/h
• Final velocity ,v = 72km/h
• Time taken ,t = 5s

To Find:-

• Acceleration ,a

Solution:-

According to the Question

It is given that bus decreases its speed from 108 km/h to 72 km/h in 5 s.

We have to calculate the acceleration of the bus.

Firstly we change the unit here

Initial velocity = 108×5/18 = 30m/s

Final velocity ,v = 72×5/18 = 20m/s

Now, Calculating the acceleration of the bus .

• a = v-u/t

where,

• v is the final velocity
• a is the acceleration
• u is the initial velocity
• t is the time taken

Substitute the value we get

→ a = 20-30/5

→ a = -10/5

→ a = -2m/s²

Here negative sign show retardation

• Hence, the acceleration of the bus is 2m/s².

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Answer 2

Answer:-

• initial velocity=108km/h=u
• Final velocity=72km/h=v

Convert both to m/s

$\\ \sf\longmapsto 108\times \dfrac{5}{18}=30m/s$

$\\ \sf\longmapsto 72\times \dfrac{5}{18}=20m/s$

• Time=5s=t

We know that

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

$\\ \sf\longmapsto Acceleration=\dfrac{20-30}{5}$

$\\ \sf\longmapsto Acceleration=\dfrac{-10}{5}$

$\\ \sf\longmapsto Acceleration=-2m/s^2$