Here's why:
* Newton's First Law: An object at rest stays at rest, and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.
* Constant velocity: Since the object is moving at a constant velocity, this means its acceleration is zero.
* Newton's Second Law: Force equals mass times acceleration (F = ma). If acceleration is zero, the net force acting on the object must also be zero.
* Forces involved: The pulling force is acting in one direction, and the force of friction is acting in the opposite direction. Since the net force is zero, these two forces must be equal in magnitude.
Therefore, for the object to move at a constant velocity, the pulling force must be equal and opposite to the force of friction.
