Work or No Work; Power

Also called

work · work done · no work · power · joule · watt · force times displacement · W = F s cos theta · work against gravity · carrying a load is no work · zero work · rate of doing work · energy · lifting a box · कार्य · शक्ति · ऊर्जा

Topics

• Work is done when a force moves its point of application: W = F × s, measured in joules (1 J = 1 N m).
• Pushing a box along the floor is work: the force and the displacement are in the same direction.
• Carrying a load on level ground does no work on it: the upward force from the hands is at 90° to the motion.
• Lifting a box of weight mg through a height h does work mgh against gravity.
• For a pull at an angle θ only the part of the force along the motion does work: W = F s cos θ.
• The vertical part of a slanting pull does no work, because the box does not move up or down.
• Power is the rate of doing work: P = W ÷ t, measured in watts (1 W = 1 J/s).
• Lifting the same box to the same height is the same work; doing it in a third of the time needs three times the power.

About this model

A GLB file of about 235 KB, shown in Lably's 3D viewer and, on a phone, placed in your room with AR. Credit: Model, science and animation: Lably (built procedurally with three.js; no downloaded meshes). | CC BY 4.0. Original geometry and animation made for Lably.

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