# Net force

The vector sum of every force on an object. It decides whether the object speeds up, slows down, turns or stays steady.

Physics (university) · Part 02: Newton's laws and forces · Card 2 of 10 · Last updated 2026-10-19

## Analogy

A tug of war: only the leftover pull wins.

## Example

**Adding forces**

50 N right
20 N left
Net = 50 - 20 = 30 N right

## In practice

If you push right with 50 N and friction pushes left with 20 N, the net force is 30 N right.

## Practice

### Flashcards

- **What does an object do when net force is zero?** It keeps a constant velocity, which may be zero.

## Questions people ask

### Does zero net force mean no forces act?

No. Many forces can act on an object while adding up to zero. A book on a table has gravity pulling down and the table pushing up with equal force. The net force is zero, so the book stays still, yet two forces are clearly acting.

### How do I add forces that point in different directions?

Split each force into x and y components, then add the x parts and the y parts separately. This gives the components of the net force. Combine them with the Pythagorean theorem for the size and with the inverse tangent for the direction.

## Related concepts

- [Newton's first law](https://studyvisually.com/learn/science/physics-university/physics-university-part-2/physics-university-part-2-concept-1)
- [Newton's second law](https://studyvisually.com/learn/science/physics-university/physics-university-part-2/physics-university-part-2-concept-3)
- [Newton's third law](https://studyvisually.com/learn/science/physics-university/physics-university-part-2/physics-university-part-2-concept-4)
- [Weight](https://studyvisually.com/learn/science/physics-university/physics-university-part-2/physics-university-part-2-concept-5)

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