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?
a. No, the friction force is not equal and opposite to your 150N push. According to Newton's third law of motion, for every action, there is an equal and opposite reaction. In this case, your 150N push on the refrigerator is the action, but the reaction force is not necessarily 150N in the opposite direction.
The friction force is what opposes the motion of the refrigerator across the floor. When you exert a force of 150N on the refrigerator, the friction force matches this force exactly, but in the opposite direction. Since you are pushing the refrigerator with a force of 150N, the friction force will also be 150N in the opposite direction to maintain a constant velocity. The friction force balances out your push and prevents the refrigerator from accelerating or decelerating.
b. No, the friction force does not make up the reaction force to your push. The reaction force to your push (150N) is actually the normal force, which is the force exerted by the floor on the refrigerator perpendicular to the surface.
When you push the refrigerator, the floor exerts an equal and opposite force on the refrigerator, which is the normal force. This force counteracts the force of gravity and prevents the refrigerator from sinking through the floor. The normal force and your push force (action) are not equal, but they have the same magnitude. The friction force, on the other hand, acts parallel to the surface and opposes the motion, but it is not the reaction force to your push.
a. No, the friction force is not equal and opposite to your 200N push. The friction force is determined by the coefficient of friction between the refrigerator and the floor, as well as the normal force acting on the refrigerator. In this case, since the refrigerator is moving at a constant velocity, it indicates that the applied force (150N) is balanced by the friction force. Therefore, the friction force must be equal in magnitude and opposite in direction to the applied force, which is 150N, not 200N.
b. Yes, the friction force acts as the reaction force to your push. According to Newton's third law of motion, for every action, there is an equal and opposite reaction. When you apply a force to push the refrigerator, the refrigerator exerts an equal and opposite force on you. The friction force between the refrigerator and the floor acts as the reaction force, balancing the force you applied to push it. So, in this scenario, the friction force makes up the reaction force to your push.