Question

what work is said to be done to increase the velocity of the car from 15 kilometre per hour to 30 km per hour if mass of car is 1000 kg?

Answer 1

Given:

The initial speed of car = 15 km/hour

The increased speed of car = 30 km/hour

The mass of car = 1000 kg

To find:

Work done to increase the speed.

Solution:

With an increase in speed, there will be an increase in kinetic energy of the car, therefore the work done to increase the speed will be equal to the change in kinetic energy of the car.

The initial speed of the car = 15 km/hour

Initial kinetic energy = 1/2 x mass x $velocity^{2}$

K.E. 1 =  112500 joules

Similarly,

The increased speed of car = 30 km/h

Finial kinetic energy = 1/2 x mass x $velocity^{2}$

K.E. 2 =  450000 joules

Therefore, change in kinetic energy = K.E. 2 - K.E.1

= 450000 - 112500

= 337500 joules

Therefore work done will be 337.5-kilojoules.

Answer 2

Answer:

Work done will be 337500 joules.

Explanation:

• In context to the question we have to find Work done to increase the speed.

• Given:

The initial speed of car  (u) = 15 km/hour

The increased speed of car(v) = 30 km/hour

The mass of car = 1000 kg

We know that, As the increase in speed, there will be an increase in kinetic energy of the car,

Therefore the work done to increase the speed will be equal to the change in kinetic energy of the car.

⇒ The initial speed of the car = 15 km/hour

Initial kinetic energy = 1/2 x mass x velocity

Initial kinetic energy = 1/2 x m x u²

Initial kinetic energy = 1/2 x 1000 x 15²

Initial kinetic energy = 225000/2

Initial K.E.  =  112500 joules

Similarly,

⇒ The increased speed of car = 30 km/h

Increased kinetic energy = 1/2 x mass x  velocity

Increased kinetic energy = 1/2 x m x v²

Increased kinetic energy = 1/2 x 1000 x 30²

Increased kinetic energy = 900000/2

Increased K.E.  =  450000 joules

Therefore, change in kinetic energy = Increased K.E. -Initial K.E.

= 450000 - 112500

= 337500 joules

Therefore work done will be 337500 joules.