Forces Are Pushes and Pulls

Lesson 1 of 11 · 5 min · Free, no account needed

What you will learn

A force is a push or a pull, measured in newtons (N). It always has a direction.
The net force is all the forces added up, with one direction counted as minus.
The net force decides what happens: net 0 N and nothing changes; otherwise the object speeds up toward the net force.

Tug of war: four kids against three adults. Does the bigger team win?
Drag the flag to where the red ribbon will be after 3 seconds.
Press Pull. Then change the teams and pull again.
Each arrow is one person's pull in newtons. The big arrow is the sum.
Three kids pull left. Turn the strong pull until the rope stands still.
Pushes and pulls have a name and a unit.
A force is a push or a pull. It is measured in newtons (N). Holding up a small apple takes about 1 N.
A force has a direction. Count one way as plus and the other as minus: here right is plus.
The net force is the sum: 750 N right and 600 N left give 150 N right. Simplified model: we count only the rope, not the ground under their feet.
Game: balance board. Hit the target net force in few moves.
Drop force tiles on the left or right of the cart. Tap your arrow to take it back (that costs a move).
Build your own set: net 30 N to the right, with at least one pull to the left.
Use three arrows or more. Your set drives the cart at the end.
Your set drives the cart. Press Play.

Lessons are interactive and need JavaScript. Turn it on to play them.