I read somewhere – a while ago – that energy was required for any matter to “do work”. Is there a neat way to define what work means, in this sense?
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The Formula For Work: W = Force x displacement Whenever a force moves an object, we say that work has been done.
Work in physics basically means moving. If a thing goes from point A to point B in space, you can say it performed work
Work is simply just the change in energy of a system.
– When you lift an object, you are giving it potential energy. You have done work on the object in lifting it
– When you slide or drag an object, you are giving it kinetic energy. Friction is doing work by taking kinetic energy away in slowing it/impeding it
– When you turn on your game boy color to pay pokemon yellow, the batteries are doing work in moving electrons from the negative terminal to the positive terminal
Just a few examples
Work is always the act of moving something against some resistive force. That might be lifting a weight uphill against gravity, or pushing a block horizontally against friction, or pulling the end of a spring against the tension in the spring, or pumping air into a container against the pressure inside that container, or pushing an aircraft against air resistance and lift-induced drag.
Edit to add: if the force acts in the direction you are moving then you can do negative work.
Work has the units of energy, so it’s either power * time or it is force * distance. Does that help? It is either the useful stuff your electrical device or engine did for you, or it’s the useful stuff your piston or muscle (or whatever) did for you. It is literally just the energy that you had a use for.
Because energy cannot be created or destroyed, when you put energy into something you get the same amount out. But almost nothing is 100% efficient, so it is sensible to divide the energy output into *useful* (work) and *not useful* (losses, e.g heat).
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