Friction occurs when two surfaces brush against one another. Rough surfaces like sandpaper create more friction and slow down movement.

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Motion is the movement of an object. We say an object is in motion if it is moving from one place to another.

In Science a force is used to make an object move or change shape. When you push a box or pull a lever you are using a force.

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A lever is a simple machine consisting of a long beam or rod (like a plank or a pole) that moves at a certain point called the fulcrum.

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