Question

A bus decreases its speed from
80 km h 1 to 60 km h in 5 s.
Find the acceleration of the bus.​

Answer 1

Question :–

A bus decreases its speed from 80 km/h 1 to 60 km/h in 5s. Find the acceleration of the bus.

To Find :–

• Acceleration of the bus.

Solution :–

Initial speed of bus,

$\sf \: u = 80 \dfrac{km}{h}$

$\sf = \dfrac{80 \times 10 \cancel{00}m}{36 \cancel{00}s}$

$\sf = \dfrac{800}{36} {ms}^{ - 1}$

Final speed of bus,

$\sf v = 60 \dfrac{km}{h}$

$\sf = \dfrac{60 \times 10 \cancel{00}m}{36 \cancel{00} s}$

$\sf = \dfrac{600}{36} {ms}^{ - 1}$

Therefore,

We know that,

$\tt \: accelertion, \: \boxed{a = \frac{v - u}{t}}$

$\tt = \frac{ \frac{600}{36} - \frac{800}{36} }{5}$

$\sf = - \frac{200}{36 \times 5} {ms}^{ - 2}$

$\sf = - \frac{200}{180} {ms}^{ - 2}$

$\sf = - \frac{10}{9} {ms}^{ - 2}$

$\sf = - 1.11 {ms}^{ - 2}$

Hence,

The acceleration of the bus = $\sf -1.11{ms}^{-2}$

Answer 2

Given:-

Initial velocity ,u = 80km/h

Final velocity ,v = 60km/h

Time taken ,t = 5 s

To Find:-

Acceleration ,a

Solution:-

⠀⠀⠀⠀⠀⠀⠀⠀⠀According to the Question

Firstly we change the unit of velocity .

Initial velocity ,u = 80 × 5/18 = 400/18 = 22.22 m/s

Final velocity ,v = 60 × 5/18 = 300/18 = 16.66

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

a = v-u/t

where,

v denote final velocity

u denote initial velocity

t denote time taken

a denote acceleration

Substitute the value we get

$:\implies$a = 16.66-22.22/5

$:\implies$a = -5.56/5

$:\implies:$ a = -1.12 m/s²

here, negative sign show retardation

Hence, the acceleration of the bus is approximately 1.12 m/s²