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Types of Friction. Types of Friction. Kinetic Friction Is friction between moving surfaces Sliding Rolling Fluid Static Friction When a force is applied to an object but does not cause it to move. Pushing Books. Try pushing a pile of five books across your desk with one finger
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Types of Friction • Kinetic Friction • Is friction between moving surfaces • Sliding • Rolling • Fluid • Static Friction • When a force is applied to an object but does not cause it to move
Pushing Books • Try pushing a pile of five books across your desk with one finger • Place five pens under the books, is it easier or harder to move the books now?
Ways to Reduce Friction • Switching From sliding kinetic friction to rolling kinetic friction • Example: Placing a large, heavy box on a cart with wheels to move it instead of pushing it • Lubricants: Substances that are applied to surfaces to reduce friction between surfaces • Example: Butter in a pan while cooking so that food does not get stuck • Example: Adding water to a slide will make you go faster because the friction is reduced
Soapy Hands • Who can open a pickle jar? (or a jelly jar, or a cherry jar, or whatever kind of jar you wish!) • Who can open a pickle jar with soap on their hand? • It is easier or more difficult with soap?
Ways to Increase Friction • Make surfaces rougher • Putting salt on patches of ice in the winter so that you do not slip • Wearing gloves in football so that you can catch the ball more easily • Increase the force pushing the surfaces together • Pressing down harder while scrubbing a pan • Sanding wood with sandpaper will work better if you are pressing down with more force