Friction: static and kinetic

In what way can friction be reduced?

• By keeping the area dry

• By adding a lubricant like oil

• By pushing instead of rolling

• increase the surface area

Which of these is an example of sliding friction?

• a badminton shuttlecock flying over the net

• a basketball rolling across a wooden floor

• a flying kite pushed by a gentle breeze

• a hockey puck moving across the ice

Friction is a force that acts in an ___________ direction of movement.

• similar

• opposite

• parallel

• north

Which of the following factors affect the amount of friction between two objects?

• type of surface & pressure applied to the surface

• distance between the objects

• mass of the objects

• temperature of the objects

Which of the following is an example of friction that is harmful?

• Pencil marking on paper

• sand placed on ice in the winter

• Engine parts wearing out

• Using an eraser to erase marks

When most objects with smooth surfaces rub, there is __________friction.

• equal

• more

• less

As the wheels of a train move along the train tracks, what type of friction exists between the wheels and the tracks?

• static friction

• fluid friction

• sliding friction

• rolling friction

Why does a flat piece of notebook paper take longer to reach the ground than an identical piece of notebook paper crumpled into a ball?

• The frictional force of air has more effect on the falling flat piece of paper.

• The frictional force of air has more effect on the falling crumpled piece of paper.

• The crumpled piece of paper has more mass.

• The flat piece of paper has more mass.

Why do swimmers wear a swim cap when competing in a race?

• To represent their team

• This allows them to roll in the water

• To create a smooth surface & reduce friction

• To keep their hair dray

Which is not a way to reduce friction?

• Add more force

• Add oil or another type of lubricant

• Replace rolling with sliding

• Smooth the surface