Work

How it is used

In physics, work has a precise meaning: work is done on or by an object. If you hold a heavy bag without moving it, you do no work in the physics sense, even though you get tired. When there is an angle, W = Fd cos θ.

Example sentences

1. The crane does 50 kJ of work lifting the beam to the top of the building.

2. Friction does negative work on the sliding block, so its kinetic energy decreases.

Common collocations

• do work
• work done by
• work done on
• negative work
• work-energy theorem

Related terms

• energyThe ability of a system to do work or cause change. It comes in many forms, such as kinetic, potential, thermal and chemical, and it is measured in joules (J).
• forceA push or a pull that can change how an object moves or change its shape. It has both size and direction and is measured in newtons (N).
• powerThe rate at which energy is transferred or work is done, in other words energy per second. It is measured in watts (W), where one watt is one joule per second.
• displacementThe straight-line distance from an object's starting point to its final position, together with its direction. It is a vector, measured in metres.
• kinetic energyThe energy an object has because it is moving. It depends on mass and speed and equals one half times mass times speed squared (½mv²).

More terms: Energy, Work and Momentum

• potential energy
• conservation of energy
• momentum
• impulse
• elastic collision
• conservation of momentum
• efficiency