Question

A ladder is leaned against a smooth wall and allowed to slip on a frictionless floor. Which figure represents the trace of its COM

• A.
• B.
• C.
• D.

Answer 1

The correct option is A

The explanation for the correct option:

Option A:

1. Center of mass (COM) of a body is the point of the body at which the whole mass of the body is assumed to be concentrated.
2. COM might not necessarily be in the centre of the body.
3. For a ladder, the COM of it comes out to be as the midpoint of the length of the ladder.
4. When the ladder slips down, or in case of any motion, COM does not change.
5. When the ladder slips, it moves towards the left because of the net force.
6. The net force is because of the weight and the normal force.
7. COM also traces a path which is shown in option A. Therefore option (A) is correct.

The explanation for incorrect options:

Option B:

In option B, the path would be that way if the ladder would have net force on the right side.

Option C:

In option C, the path of COM cannot be a straight path and would be this way if there would be no net force

Option D:

This cannot be the case if the ladder slips down because we know that the COM does not change.

Therefore the above options are incorrect.

And the correct option is option (A).