Question

A rectangular block has dimensions 8 m × 4 m × 2 m. It has a mass of 100 kg. It is initially on the ground with the shortest side vertical. If it is to the turned so that the longest side is vertical, the work done is equal to? $(take g=9.8m/s^{2})$

Answer 1

Hyy Dude

3kJ.

Explanation:

The work done will be the difference in the potential energy of the two cases. Which will be P.E2-P.E1.

Since, we know that the potential energy is equal to the mgh where m is the mass of the body, g is the acceleration due to gravity and h is the height of the center of mass. So, here for the first case the height will be 2/1 which is 1m and for the second case the height will be 8/2 which is 4m.

So, the work done is mg(h2-h1) which is 100*10(4-1) which on solving we will get that 3000 Joules or 3 kJ.

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