Frictional force

Friction is a force that acts in the ______ of the movement

• opposite the direction

• same direction as

• parallel direction

Frictional force _____ and eventually stops moving objects.

• pulls down

• accelerates

• speeds up

• slows down

Frictional force depends on two things. Choose the two answers.

• size of the objects

• weight of the objects

• roughness of the objects

• phase matter of the objects

The rougher the two surfaces are, the greater the frictional force between them.

• True

• Falce

The heavier the object is, the smaller the frictional force acting on it.

• True

• False

Which of the following is an ADVANTAGE of frictional force?

• Frictional force wears out tires.

• Engines of cars need to put extra effort to continue moving fast.

• It allows us to hold objects.

Which of the following is a DISADVANTAGE of frictional force?

• Frictional force wears out the bottom soles of shoes.

• Frictional force allows us to light a match.

• Friction allows objects to move without slipping.

Which is a way to INCREASE FRICTION?

• using of lubricants

• putting more threads on a car tire

• using of round and smooth spherical objects like rollers, wheels, and ball bearings

Which is a way to REDUCE FRICTION?

• using lubricants

• putting more threads on car tires

• increasing the roughness of shoe soles

Air resistance is a frictional force.

• True

• False