Question

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

Answer 1

Answer:

156375 j .

Step-by-step explanation:

Mass of the car , m = 1500 kg ,

initial velocity of car , u = 30 km h-¹

= 30×1000 m

___________

60×60s

= 8.33 m s-¹.

Similarly , the final velocity of the car ,

v = 60 km h-¹

= 16.67 m s-¹.

Therefore , the initial kinetic energy of the car ,

Eki=

1

____ mu²

2

1

___ ×1500 kg × ( 8.33 m s-¹)²

2

= 52041.68 J.

Thus , the work done = Change in kinetic energy

= Ekf - Eki

= 156375J.

Answer 2

Answer:

Work done is 156250 J.

Explanation:

Given,

The mass (m) of the car is 1500 kg.

Initial velocity of car = u = 30 km / hr = 30 * 5/18 = 25 / 3 m/s

Final velocity of car = v = 60 km / hr = 60 * 5/18 = 50/3 m/s

To find: The work to be done to increase the velocity of a car from

30 km h-1 to 60 km h^-1

Solution:

Initial kinetic energy = Ki = 1/2mu² = 1/2*1500*25/3 * 25/3 = 156250/3 J

Final Kinetic energy = Kf = 1/2mv² = 1/2*1500*50/3*50/3 = 625000/3 J

Work done can be given as change in Kinetic Energy,

i.e W = ΔK.E

or, W = Kf -  Ki

or, W = 625000/3 - 156250/3

or, W = 156250 J

Therefore, Work done is 156250 J.