Question

2. 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

Given:-

Initial velocity(u)=80km/h

=80×5/18

=200/9 m/s

Final velocity(v)=60km/h

=60×5/18

= 150/9 m/s

Time(t)=5s

To find:-

Acceleration(a)

Solution:-

a=(v-u)/t

a=(150/9-200/9)/5

a=(-50/9)/5

a=-10/9m/s or -1.11 m/s

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