Question

The velocity of a car increases from 54 km/hr to 72 km/hr. If the mass of the car is 1500 kg ,find the work done to increases the velocity?

Answer 1

using work energy theorem change in ke is wd

Answer 2

Given: Mass (m)= 1500kg

[1km/hr= 1000/3600 m/sec= 5/18 m/sec]

Initial velocity (u)= 54km/hr

= 54× 5/18

= 15m/s

Final velocity (v)= 72km/hr

= 72× 5/18

= 20m/s.

To find: work done to increase the velocity= ?

Formula: Work done to increase velocity= Change in K.E

Change in K.E=½ mv²- ½ mu²

Solñ: Change in K.E= ½ mv²- ½ mu²

= ½ m(v²-u²)

= ½× 1500[ (20)²- (15)²]

= 750× [400- 225]

= 750× 175

= 131250J

Work done to increase the velocity= 1312500J.