suppose you exert 150N on your refrigerator and push it across the kitchen floor at constant velocity.
a. is the friction force equal and opposite to your 200N push? explain
b. does the friction force make up the reaction force to your push?
I am growing tired of seeing this ridiculous question. Fire your instructor.
To answer these questions, we need to understand the concept of forces and Newton's third law of motion.
a. According to Newton's third law of motion, for every action, there is an equal and opposite reaction. When you exert a 150N push on the refrigerator, there will indeed be a friction force opposing your push. However, it doesn't necessarily mean that the friction force will be equal to the magnitude of your push.
In this case, since the refrigerator is moving at a constant velocity, we can conclude that the net force acting on it is zero. This means that the friction force is equal in magnitude but opposite in direction to your push (150N), canceling out the effect of your push. Therefore, the friction force will be 150N in the opposite direction of your push.
b. The reaction force to your push is referred to as the normal force. When you push the refrigerator, the floor exerts a reaction force on the refrigerator to keep it in contact with the floor. This reaction force acts perpendicular to the floor's surface and is called the normal force. The friction force, however, is not the reaction force to your push. The friction force opposes the motion and acts parallel to the floor's surface.
So, in summary:
a. The friction force is equal in magnitude but opposite in direction to your push (150N).
b. The reaction force to your push is the normal force, not the friction force.