Friction Pt 4

State Newton’s Third Law of Motion

For every action there is an equal and opposite reaction

What is Friction?

The force the opposes motion between two surfaces that are touching one another

What causes Friction?

The surfaces interlock because of the ridges on objects

Fluid Friction

A force of friction between an object moving through a fluid (air or water )

Static Friction

the friction between two surfaces that are not moving past each other

Sliding friction

the force that opposes the motion of two surfaces sliding past one another

Rolling Friction

the friction between a rolling object and the surface it rolls on

Which type of non-fluid friction is the greatest? Which it the least? And, Why?

• Static friction: greatest due to frictional forces needing to overcome to began motion

• Rolling Friction: least as very little surface stays in contact long enough for static interlock

Identify two factors that affect frictional forces and explain how these factors affect friction?

• The kind of surface - rougher surfaces interlock easier

• The forces pressing them together - the stronger the force, the more friction

Give two examples of ‘fluid’ friction

Swimming, cannoning, swimming

Explain why a car slows down when the driver releases the gas pedal. Does this violate Newton’s First law?

A car slows down because of the friction of the road. This does not violate Newton’s first law because the unbalanced force in the law is friction.

What is Centripetal Force?

A force directed toward the center of the circle for an object moving in a circular path

How does ice on the road reduce the centripetal force acting on a car going through a curve on the road?

Because the tires don’t have any groves to grip onto (the ice takes away the friction
) so the car would continue in the direction it was going in because of Newton’s First Law

What is the centripetal force acting on the moon that keeps it in orbit around the earth?

Gravity

2 - because the rope isn’t controlling the ball anymore so because of the balls inertia it would continue in the direction it was going in