Question

(ii) calculate the amount of work required to stop a car of 1000 kg moving with a speed of 72 km/hr.

Answer 1

Answer:

Work required to stop a car is 400000 Joule or 400 kilojoule.

Explanation:

Given,

m = 1000 kg

v = 72 km/hr

To convert km/hr into m/s , we multiply it by 5/18.

v = (72 × 5)/18

v = 4 × 5 m/s

v = 20 m/s

W = FS

W = maS

W = mSv/t [a = v/t]

W = mv.v [v = S/t]

W = mv^2

W = 1000 × (20)^2 Joule

W = 1000 × 400 joules

W = 400000 joules

W = 400000 joules or 400 kilojoule

Here,

W is the work done.

F is the force required.

S is the displacement.

m is the mass of car.

v is the velocity of car.

a is the acceleration of car.

Hence,

Work required to stop a car is 400000 Joule or 400 kilojoule.