Friction and Drag

Which correctly describesthe static and dynamic friction experienced

by the bobsled asthe team pushes off at the start but before the

bobsled beginsto move?

• A. The static friction is equal to the dynamic friction.

• B. The static friction islarger than the dynamic friction.

• C. The static friction issmaller than the dynamic friction.

• D. The static friction staysthe same and the dynamic friction gradually

Which force(s) act to slow down a runner asthey accelerate out of the

blocks at the start of a 100m sprint?

I. Air resistance

II. Ground reaction force

III. Push force

• A. I only

• B. I and II only

• C. II and III only

• D. I, II and III

Climbers put chalk on their handsto increase the grip between their

fingers and the climbing surface.The chalk absorbs body oils and

sweat.Which describesthe changesin friction caused by the chalk?

• A. The chalk increases the coefficient of static friction.

• B. The chalk increasesthe normal force of the climber.

• C. The chalk decreasesthe coefficient of static friction.

• D. The chalk decreasesthe coefficient of dynamic friction.

The diagram shows a cyclist lowering their body close to the bike

frame.

• A. Wave drag

• B. Form drag

• C. Dynamic drag

• D. Surface drag

Which would reduce the coefficient of friction?

• A. An ice skatersharpenstheirskates.

• B. A rock climber applies chalk to their hands when climbing.

• C. A baseball player uses cleats(studs) on their boots.

• D. A golfer wears a glove when hitting the ball.

Four climbers compare the grip quality of their boots.Which climber’s

boots have the greatest friction force?

• A

• B

• C

• D

In the sport of curling, team membersslide a large stone acrossice

towards a target.Which isrelevant to the stone asit moves acrossthe

ice?

• A.The coefficient of static friction

• B.The coefficient of dynamic friction

• C.The coefficient of static drag

• D.The coefficient of dynamic drag

What is drag?

• A. A dimensionlessscalar quantity, which isthe ratio of friction and

  normal reaction force

• B. A force applied to attempt to move a stationary object

• C. A force that acts parallel to the interface of two surfacesthat are in

  contact

• D. A force acting to oppose the motion of an object through a fluid

What is an example of an athlete reducing form drag?

• A. A cyclist adopting a low profile position

• B. A swimmer staying underwater for as long as possible at the start of

  the race

• C. A swimmer using a shark-skin suit

• D. A soccer player using soccer boots on a grass surface

Which opposing force reduces the motion parallel to the interface of

two surfaces in contact?

• A. Friction

• B. Newton’s third law

• C. Normal reaction force

• D. Lift force