Idea 2of 6Builds onNothing needs a push to keep goingHow fast the speed changes
Change needs a net force
Fifteen newtons left over on five kilograms. How fast a change?
Today you'll discover
- what a leftover force does to the speed
- double the force, and what happens
- the rule that joins force, mass and the change
Think first15 N left over on a 5 kg crate
The 15 N net force gives 3 m/s². Make the net force 30 N. The acceleration?
Predict first, then drag the sliders. Watch what the bars do.
A box on a floor with four force arrows and a heavier net arrow beside it. After a prediction, the second-law bench opens with sliders for net force and mass and a bar chart of the acceleration for the chosen mass, double it and half it. The last step asks the acceleration of a twenty-kilogram crate.
See the whole ideathe big idea and the key word, in one place
The big idea
Acceleration is the net force divided by the mass.
Easy to get wrongA net force sets how fast the velocity changes, not the velocity. A small force for a long time can build a huge speed.
Key word
- second law
- Newton's second law: a = Fnet ÷ m, acceleration in the direction of the net force
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?
- Find the acceleration from a net force and a mass, or the net force from the other two.