Answer: (a) When Sarah pulls on one end of the rope with a force of 100 N, and her friend Jane pulls on the other end with an equal force of 100 N, the rope experiences a tension force. The tension force acts along the length of the rope, pulling it in opposite directions from each end. As a result, the rope remains taut and does not move in any particular direction.
(b) Without the given picture, it's not possible to identify specific labels for P, W, N, and f. However, I can provide explanations of what these labels generally represent:
- P: P typically represents the symbol for force, which can be applied in various directions.
- W: W often represents the symbol for weight, which is the force exerted by gravity on an object. It acts vertically downward.
- N: N typically represents the symbol for the normal force, which is the force exerted by a surface to support the weight of an object resting on it. It acts perpendicular to the surface.
- f: f usually represents the symbol for frictional force, which is the force that opposes the motion or attempted motion of an object in contact with another surface.
(c) The box will move when an external force overcomes the opposing forces acting on it, such as friction and the normal force. If the applied force (P) is greater than or equal to the sum of the frictional force and the normal force, the box will start to move. To move the box with less effort, one can reduce the frictional force. This can be achieved by using lubricants or reducing the roughness of the surfaces in contact, thereby minimizing the resistance to motion. Additionally, applying the force at an angle or using mechanical advantage, such as using a lever or pulley system, can also help in moving the box with less effort.