Net force
The vector sum of every force on an object. It decides whether the object speeds up, slows down, turns or stays steady.
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Analogy
A tug of war: only the leftover pull wins.
Example
50 N right20 N leftNet = 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.