Question

On a frictionless tabletop, a force is applied to an object: the object's velocity is horizontal and the force is perpendicular to the tabletop. Which of the following is true?

1. The total energy of the object does not change.
2. The applied force is friction.
3. 44 The force does work on the object.
4. There cannot be more than one force on the object.

Answer 1

Answer:

The total energy of the object does not change is the true statement.

Explanation:

1. The force applied to the object is perpendicular to the movement so doesn't work on it, assuming the table is at the same height in all of its points the only energy we have to analyze is the kinetic energy $K=\frac{mv^{2}}{2}$, because the table top is frictionless by Newton's first law the velocity (v) doesn't change so the kinetic energy is constant and the total energy too.

2. There's no friction in this situation

3. As stated on 1. because the applied force is perpendicular to the movement of the object, there force doesn't work on it.

4. There are over one force on the object, the weight and the normal force table top exerts to the object.

So the only true statement is 1.