Idea 2of 6Builds onThe ability to make changeA push or a pullEvery metre counts
Paying with a push
Push a crate 4 m with 50 N. What was spent?
Today you'll discover
- what a push over a distance buys
- why the distance matters as much as the push
- the unit the purchase is counted in
Think firstA 50 N push moves a crate 4 m
Same 50 N push, but the crate moves 8 m instead of 4 m. What you spend?
Decide first, then press Next. Watch the product appear in the corner.
A crate on a floor with a solid arrow from its centre pointing right, the push, and a longer arrow along the floor beneath it, the distance moved. After a prediction, the product of the two is printed in the corner. The last step halves the push and doubles the distance and asks for the work.
See the whole ideathe big idea and the key word, in one place
The big idea
Work is force times the distance moved.
Easy to get wrongWork is not effort. Pushing hard against a wall that never moves transfers no energy to the wall, however tired you get.
Key words
- work
- energy transferred by a force along the direction of motion: W = F Δd, in joules
- joule
- the unit of energy and of work, symbol J: one newton acting over one metre
About this modelOnly the part of the force along the motion does work: W = F Δd cos θ.
Only the part of the force along the motion does work: W = F Δd cos θ.
Ready to use it?
- Find the work done by a given force over a given distance, in joules.