Question

what is the work done when the velocity increases from 30 km/hr to 60 km/hr mass is 1500 kg

Answer 1

We have, work,

W = ∆K

where K is the kinetic energy. But,

W = K2 - K1

W= [m((v2)² - (v1)²)] / 2

W = [m(v2 + v1)(v2 - v1)] / 2

We're given,

m = 1500 kg

v1 = 30 km h^(-1)

v2 = 60 km h^(-1)

So,

W = [1500(60 + 30)(60 - 30)] / 2

W = [1500 × 90 × 30] / 2

But just a minute... Here the velocities are in km h^(-1).

We've to convert them in m s^(-1), we know we've to multiply 5 / 18 to it. But in the final equation two velocities are multiplied so there's km² h^(-2) actually kg km² h^(-2), so we've to convert it in kg m² s^(-2) [simply Joule, J] by multiplying (5 / 18)² = 25 / 324 to it.

So,

W = (1500 × 90 × 30 × 25) / (2 × 324)

W = 156250 J

W = 156.25 kJ

Answer 2

Given :

• A car from 36 km/hr to 72 km/hr, Mass of car is 1500 kg.

To find :

• What is work done.

Using formula :

★ Work done = Force × Distance.

Calculations :

→ 0.5 (v² - u²)

→ 0.5 × 1500 {(60 × 5/18)² - (30 × 5/18)²}

→ 156250 J

Therefore, the work done is equal to 156250 Joule.