All Textbook Topics - Forces introduction - Types of forces - Friction is a force that resists motion
Friction is a force that resists motion
Friction always acts in the opposite direction to motion, hence in a way to resist the motion.
In this first example, friction is resisting the pulling force trying to pull the block to the right:
![](https://cdn.figureoutphysics.com/text/15850817183ei8xHu61o5g4tUjzSvNp0LKPZsEr2.png)
In this second example friction is resisting the motion of the trolley:
![](https://cdn.figureoutphysics.com/text/1585081718jmI3xVCO7Hly2fBpMvWT1tr6UgD9kz.png)
In this final example, the trolley is moving down the slope, so friction is acting up the slope as it is resisting the motion:
![](https://cdn.figureoutphysics.com/text/1585081718AYmn7yPfsl3uxNqkV96jJ1UpLXFwIo.png)
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