Question

A uniform rod of length $4m$ and mass $200Kg$ is lying horizontal on the ground. The work done in keeping it vertical with one of its ends touching the ground, will be:

• A. $3920$
• B. $3000$
• C. $3500$
• D. $3700$

Answer 1

The correct option is A $3920$

The work done is equal to change in its gravitational potential energy,

So W=mgh where h is the height of centre of mass,

So W=200$\times 2\times 9.8=3920J$