IB SEHS Topic 10.0

Friction occurs when

• Two surfaces repel each other

• Two surfaces are in contact and inhibit movement

• Two surfaces attract each other

• Two surfaces are parallel to each other

The force of friction is

• The force applied to move a stationary object

• The force opposing motion between two surfaces

• The force that attracts two surfaces together

• The force that repels two surfaces apart

The coefficient of friction (COF) is

• The force of friction divided by the normal force

• The force of friction multiplied by the normal force

• The ratio of velocity to acceleration

• The ratio of mass to acceleration

The coefficient of static friction acts on an object when

• The object is at rest

• The object is in motion

• The object is sliding over a surface

• The object is accelerating

The coefficient of dynamic friction acts on an object when

• The object is at rest

• The object is in motion

• The object is sliding over a surface

• The object is accelerating

Friction improves a sprinter's performance by

• Increasing slipping between track and footwear

• Minimizing forward motion

• Preventing slipping

• Reducing surface area in contact with the ground

Studs or cleats in football boots are used to

• Increase friction

• Decrease friction

• Improve aerodynamics

• Reduce weight

Surface drag is caused by

• Interaction between the surface and fluid

• Motion of an object through a fluid medium

• Displacement of fluid to form waves

• Streamlining of the body

How can surface drag be minimized?

• By reducing the interaction between surface and fluid

• By adopting a low profile position

• By increasing the surface area facing the direction of motion

• By creating waves at the interface between air and water

Form drag can be minimized by:

• Increasing the surface area facing the direction of motion

• Adopting a low profile position

• Reducing the interaction between surface and fluid

• Creating waves at the interface between air and water