Idea 1of 7Builds onThe touching testThe net arrow
The drag against the slide
A crate slides along. Does the floor only hold it up?
Today you'll discover
- a second thing the floor does to a sliding crate
- which way that push runs
- the name for the drag along a surface
Think firstA hand pushes a crate along a floor
The crate slides along the floor. Does the floor do anything besides hold it up?
Decide first, then press Next. Watch which way the floor's second arrow points.
A box on a floor with a dot at its centre and a hand's push drawn as an arrow to the right. After a prediction a second arrow from the floor appears, pointing left along the surface, then both of the floor's arrows are shown together and the drag is named. The last step removes the hand and asks whether the drag goes on.
See the whole ideathe big idea and the key word, in one place
The big idea
Friction is the surface's drag against the slide.
Easy to get wrongFriction is not the crate's motion wearing out. It is a real force from the floor, and it keeps acting after the hand lets go. That is what stops the crate.
Key word
- friction
- the force along a surface that opposes the sliding of one surface over another; symbol Ff
About this modelArrows are forces, not motion: a box can move with no arrow pointing its way.
Arrows are forces, not motion: a box can move with no arrow pointing its way.
Ready to use it?
- Draw the friction on a described sliding object with its direction.