A car weighing 5 tons is moving at a speed of 72 km / h. What work must be done to stop it?

Given:

m = 5 t = 5000 kg;

V = 72 km / h = 72000/3600 = 20 m / s.

Find:

A – ?

Solution:

A = Ek2 – Ek1;

A = mV2 ^ 2/2 – mV1 ^ 2/2;

A = 5000 * 0 ^ 2/2 – 5000 * 20 ^ 2/2;

A = 0 – 5000 * 400/2;

A = – 1,000,000 J.

Answer: 1,000,000 J.




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