AI Tutor
Imagine trying to push a heavy couch across the living room by yourself, and it barely moves. But when your friend pushes in the exact same direction, the couch suddenly glides across the rug!
Every push or pull is a force, measured in units called newtons (NN), named after the scientist Sir Isaac Newton, who formulated the laws of motion in 1687.
When more than one force acts on an object at the same time, we combine them into a single total called the net force.
How do we combine two pushes when they work together?

Forces in the Same Direction

When forces act along the same line in the same direction, they help each other. Because both pushes work toward the same goal, we simply add them together.
If you push right with 5 N5\text{ N} and your friend pushes right with 3 N3\text{ N}, the net force is 5 N+3 N=8 N5\text{ N} + 3\text{ N} = 8\text{ N} to the right, causing the box to speed up toward the right.
What happens if your friend pushes against you from the opposite side instead?

Forces in Opposite Directions

When forces act in opposite directions, they fight against each other. To find the net force, you subtract the smaller force from the larger force.
The object always speeds up in the direction of the larger force, because that side wins the tug-of-war.