Question

A rod of mass M and length L is lying on a horizontal table.
Work done in making it stand on one end will be:​

Answer 1

Answer:Mgl/2

Explanation:

We need to concentrate on center of mass here

Center of mass is a point where we assume all the mass is concentrated

Matter of fact, at the center of any symmetrical center of a body

As the rod is sleeping on the floor

Energy stored is zero

When it's made to stand it's center of mass raised by L/2 distance high from ground

So work done is force *displacement

MgL/2 is the correct answer

Answer 2

Explanation:

Here we might get confused that why taken at l/2 but it is fact that of symmetrical or uniform body we have assume it's whole mass at one place(COM)