Question

A bus decreases its speed from 80 km/h to 60 km/h in 5 s. Find the acceleration of the bus.(show all steps neccecary)

Answer 1

Answer:

Explanation:

Solution,

Here, we have

Initial velocity, u = 40 km/h = 40 × 5/18 = 22.2 m/s

As km/h to m/s = 5/18

Final velocity, v = 60 km/h = 60 × 5/18 = 16.7 m/s

Time taken, t = 5 seconds

To Find,

Acceleration, a = ?

According to the 1st equation of motion,

We know that

v = u + at

So, putting all the values, we get

v = u + at

⇒ 16.7 = 22.2 + a × 5

⇒ 16.7 - 22.2 = 5a

⇒ - 5.5 = 5a

⇒ - 5.5/5 = a

⇒ a = - 1.1 m/s².

Hence, the acceleration of the bus is - 1.1 m/s².

Answer 2

Solution :

We know that initially velocity of the bus is,u=80km/hr=

40km/hr*5/18=22.2m/s,

And the final velocity of bus=60kmhr=60kmhr*5/18=

16.6m/s.

Time taken by the bus t=5 seconds ,

Let Acceleration of bus be a .

According to the acceleration formulae :

Acceleration=Change in velocity/time ,a=v-u/t

Here u is initiall velocity, v is final velocity

[ Do cross multiplication]

=> at=v-u

=> so v=u+at

Here the v=u+at is the first equations of motion

→ v=u+at

→ 16.6=22.2+5a

→ 16.6-22.2=5a

→ -5.5 or -5.7 =5a

→ a= -1.1 9r -1.898

ADDITIONAL INFORMATION:

• v=u+at
• v²-u²=2as
• s=ut+1/2at²