Explain why should torques, not forces, play essential roles in the following actions.
(a) open or close a door
(b) tighten or loosen a screw using a wrench
c) "Give me a place to stand, and I shall move the Earth with it"
(a) rotation around sticky hinge
(b) rotation of screw
(c) rotation around fulcrum of lever
Torques, not forces, play essential roles in the actions mentioned for the following reasons:
(a) To open or close a door: When you push or pull on a door, you are applying a force, but it is the torque that determines whether the door opens or closes. Torque is a rotational force, or moment, that causes an object to rotate around an axis, in this case, the hinges of the door. When you apply a force at a distance from the pivot point (hinge), a torque is generated. The direction and magnitude of this torque will determine whether the door opens or closes. So, by exerting the right amount of torque, you can control the movement of the door.
(b) To tighten or loosen a screw using a wrench: When you use a wrench to tighten or loosen a screw, torques are crucial because they allow you to transmit the force to the screw effectively. Torque is required to rotate the screwdriver or wrench, and this rotational force is what tightens or loosens the screw. The longer the handle of the wrench, the greater the torque that can be applied. By applying a sufficient amount of torque in the right direction, you can ensure that the screw gets tightened or loosened correctly.
(c) "Give me a place to stand, and I shall move the Earth with it": This famous statement by Archimedes highlights the importance of torque in moving massive objects. Torque is crucial because it allows us to generate a rotational force around a pivot point even when dealing with immovable objects. In this scenario, if you have a solid and stable platform to exert a force, you can leverage the torque generated by that force to move objects much more massive than yourself. By applying a sufficient amount of torque in the right direction, you can create a rotational force capable of moving the Earth when utilizing a proper pivot point or leverage.
In summary, torques play essential roles in these actions because they determine the effectiveness and direction of the rotational force required to open or close a door, tighten or loosen a screw, or move massive objects, given a stable platform and proper leverage.