Question

Question : What is the work to be done to increase the velocity of a car from 30km h-1 to 60 km h-1 if mass of car 1500 kg ?​

Answer 1

Answer ;-

156250 J

Given :-

• Mass of the body is 1500 kg
• Velocity of car changes from 30 km/hr - 60km /hr

To find:-

• Work done by the body

Solution :-

As we know that work done by the body is may be the Kinetic energy , Potential energy ,  elastic potential energy etc .

So, According to the Question

Work done by the body is Change in Kinetic energy .

W = 1/2 m (v²-u²)

Initial Velocity is 30 km/hr and Final velocity is too 60km/hr Lets convert into m/s

Converting km/hr to m/s

30 km/hr = 30×5/18

= 10 × 5/6

= 5× 5/3

= 25/3 m/s

30 km/hr =  25/3 m/s

60 km.hr = 60×5/18

= 20 × 5/6

= 10 ×5/3

= 50/3 m/s

60 km/hr = 50/3 m/s

Substituting the values ,

m = 1500 kg

v = 50/3 m/s

u = 25/3 m/s

W = 1/2 (1500){ (50/3)² - (25/30)²}

W = 750 ( 2500/9 - 625/9)

W = 750(2500-625/9)

W = 750(1875/9)

W = 250 (1875/3)

W = 250 (625)

W =156250 J

So, work done by the body is 156250 J

Answer 2

Answer :  

W = 1/2 m (v²-u²)  

W = 1/2 (1500){ (50/3)² - (25/30)²}  

W = 750 ( 2500/9 - 625/9)  

W = 750(2500-625/9)  

W = 750(1875/9)  

W = 250 (1875/3)  

W = 250 (625)  

W =156250 J

∴ work done is 156250 J