Understanding Friction

Which of the following statements is false?

• Friction slows things down

• Friction is never useful

• Friction can stop things from moving

Why is it easier to move water through a hose than grease?

• Since grease is slippery, it actually moves easier than water

• Because you would never move grease through a hose in the first place

• Water has less viscosity than grease and thus less fluid friction

A girl starts sliding down a grassy hill but stops halfway down. What force stops her sliding down?

• Weight

• Gravity

• Friction

True or False: Humans have been able to eliminate all friction in certain systems by using materials such as Teflon, oil, steel, or ice.

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OFF

Which of the following is an example of an attempt to increase friction?

• Spreading grit or sand on icy roads

• Squirting oil into door hinges

• Waxing the underneath of skis

On which surface will a soccer ball travel the least distance?

• Carpet

• Polished wood

• Ice

A puck slides along an icy surface. What makes it slow down?

• There wasn’t enough force to keep it moving

• The surface of the puck and ice rubbing against each other

• It runs out of electricity

True or False: Friction can occur in liquids, gases, and solids.

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OFF

If you poured oil onto a wooden surface, the friction of the wood surface would…

• Remain the same

• Decrease

• Increase

Which of the following statements is true?

• Friction is a force that only occurs on rough surfaces

• Friction is a force that only occurs between solids

• Friction is a force that only occurs when surfaces touch each other