you drag a heavy box along a rough horizontal floor by a horizontal rope. Identify the reaction force to each of the following forces: (a) the pull of the rope on a box (b) friction force oin the box (c) the normal force on the box (d) weight of the box
(a) The reaction force to the pull of the rope on the box is the box pulling back on the rope, which we like to call "rope burn revenge".
(b) The reaction force to the friction force on the box is the box pushing against the floor, desperately searching for a smooth spot to ride on.
(c) The reaction force to the normal force on the box is the floor pushing back on the box, saying, "Stay down, box! You shall not float!"
(d) The reaction force to the weight of the box is the Earth grumbling and saying, "Why do you vex me with your heavy box antics?"
To identify the reaction forces acting on the box, you need to understand Newton's third law of motion, which states that for every action, there is an equal and opposite reaction.
(a) The pull of the rope on the box:
The reaction force to the pull of the rope on the box is the force exerted by the box on the rope. According to Newton's third law, these two forces are equal in magnitude and opposite in direction. So, the reaction force to the pull of the rope on the box is the force exerted by the box on the rope.
(b) Friction force on the box:
When you drag a heavy box along a rough floor by a rope, the box experiences a friction force opposing its motion. The reaction force to this friction force is the force exerted by the box on the floor. Again, according to Newton's third law, these two forces are equal in magnitude and opposite in direction. So, the reaction force to the friction force on the box is the force exerted by the box on the floor.
(c) The normal force on the box:
The normal force is the force exerted by a surface in contact with an object perpendicular to that surface. In this case, the reaction force to the weight of the box is the normal force. The box is resting on the horizontal floor, so the normal force is the upward force exerted by the floor on the box, opposing the weight of the box.
(d) The weight of the box:
The reaction force to the weight of the box is the force exerted by the box on the Earth. This force is known as the gravitational force and it is the force that pulls the box downward towards the Earth.
In summary:
- The reaction force to the pull of the rope on the box is the force exerted by the box on the rope.
- The reaction force to the friction force on the box is the force exerted by the box on the floor.
- The reaction force to the weight of the box is the force exerted by the box on the Earth.
- The reaction force to the normal force on the box is the force exerted by the floor on the box.