Question

A bus decreases its speed from 72 kmph to 60 kmph in 5 s. Find the acceleration of the bus.

Answer 1

Answer:

0.66m/s² is the required acceleration

Explanation:

According to the Question

It is given that ,

• Initial velocity ,u = 72km/h
• Final velocity ,v = 60km/h
• Time taken,t = 5s

we need to calculate the acceleration of the bus.

Firstly we change the unit here

Initial velocity ,u = 72×5/18

Initial velocity ,u = 4×5

Initial velocity ,u = 20m/s

Final velocity,v = 60×5/18

Final velocity ,v = 16.66m/s

as we know that acceleration is defined as the rate of change in velocity.

• a = v-u/t

where,

a denote acceleration

v denote final velocity

u denote initial velocity

t denote time taken

Substitute the value we get

➻ a = 16.66-20/5

➻ a = -3.34/5

➻ a = -0.66m/s²

here negative sign show retardation

• Hence, the acceleration of the car is 0.66m/s².

Answer 2

Answer:

initial velocity  v = 72km/h      = 20 m/s

final velocity   u = 60 km/h     =16.66 m/s

time                 t =5 sec.

acceleration   a = ?

Formula;

               a = (u - v)/t

               a = (16.66-20)/5

               a = -0.668 m/sec.square

"negative sign tell us acceleration decrease with time.This acceleration is also called decelleration".