Question

What work is said to be done to increase the velocity of a car from 15 km/h to 30 km/h, if the mass of

the car is 1000 kg?​

Answer 1

Answer:

Given:-

u=15km/h

v=30km/h

Mass=1000 kg

W=?

W=K.E.= ½m(v²-u²)

= ½ x 1000 x (30)²-(15)²

= ½ x 1000(900-225)

= ½ x 1000(675)

K.E.=337500J

∴ Work done =337500 Joule.

Answer 2

Given :-

Initial velocity of the car = 15 km/h

Final velocity of the car = 30 km/h

Mass of the car = 1000 kg

To Find :-

The work done by the car.

Analysis :-

Here we are given with the initial, final velocity and the mass of the car.

In order to find the work done, substitute the given values in the formula of kinetic energy showing the difference of two velocities.

Solution :-

We know that,

• u = Initial velocity
• m = Mass
• KE = Kinetic energy
• v = Final velocity
• w = Work done

Using the formula,

$\underline{\boxed{\sf Kinetic \ energy= \dfrac{1}{2} m(v^2-u^2)}}$

Given that,

Mass (m) = 1000 kg

Final velocity (v) = 30 km/h

Initial velocity (u) = 15 km/h

Substituting their values,

$\sf KE=\dfrac{1}{2} \times 1000 \times (30^2-15^2)$

$\sf KE=\dfrac{1}{2} \times 1000 \times (900 -225)$

$\sf KE=\dfrac{1}{2} \times 1000 \times 675$

$\sf KE=\dfrac{1000 \times 675}{2}$

$\sf KE=\dfrac{675000}{2}$

$\sf KE=337500 \ J$

Therefore, the work done by the car is 337500 J.