Question

A bus decreases its speed from 80km/hr to 60km/hr in 5 second .Find the acceleration of the bus??

Answer 1

EXPLANATION.

A bus decrease it's speed from 80 km/ hr

to 60 km/hr.

=> Time taken = 5 seconds.

Let initial velocity = u = 80km/hr

=> 80 X 5/18 = 200 / 9 = 22.22 m/s

Let final velocity = v = 60 km/hr

=> 60 X 5/18 = 50/3 = 16.67 m/s

From Newton first equation of

kinematics.

=> v = u + at

=> 16.67 = 22.22 + 5a

=> -5.55 = 5a

=> a = -1.1 m/s²

Answer 2

Answer:

-4km/hr/s

Explanation:

Given :

• Initial velocity,u = 80km/hr

• Final velocity,v = 60km/hr

• Time taken,t = 5 seconds

To Find :

• Acceleration,a = ?

Solution :

According to first law of motion,

$\sf{}v=u+at$

Put thier values and solve for a,

$\sf{}\implies 60km/hr= 80km/hr+a\times 5s$

$\sf{}\implies 60km/hr-80km/hr= a\times 5s$

$\sf{}\implies -20km/hr= 5s$

$\sf{}\implies -\dfrac{20km/hr}{5s}= s$

$\sf{}\therefore s = -4km/hr/s$

Therefore,acceleration is equal to -4km/hr/s or ,-1.1ms^2 if we will convert the given values in m/s but if we are converting it into m/s  we will write unit of the acceleration as km/hr/s  

☆Know more☆

$\sf{}Second\ equation\ of\ motion: s=ut+\dfrac{1}{2}at^2$

$\sf{}Third\ equation\ of\ motion: v^2=u^2+2as$