8. Friction

Question 1

Friction

Answer 1

A force that acts in an opposite direction to the motion of an object.

Question 2

What causes friction between two solids?

Answer 2

1. Type of material (μ aka., coefficient of friction)
2. Mass (Technically it is the Normal Force—F_N—because it is the surface’s reaction to mass affected by gravity.)

Question 3

Two types of sliding friction.

Answer 3

1. Kinetic Friction
2. Static Friction

Question 4

Kinetic Friction

Answer 4

1. Attempts to stop or slow moving objects.
2. If we apply a force equal and opposite to the F_kfr the object will continue moving with no acceleration (constant velocity).

Question 5

Static Friction

Answer 5

1. Must be overcome to start motion.
2. This force is reactive. It has a maximum value before motion can begin but will not always exert that value.

Question 6

Equation of kinetic friction

Answer 6

Question 7

Equation of static friction

Answer 7

Question 8

Friction affects the acceleration of an object. How?

Answer 8

Question 9

We describe friction when falling through air as…

Answer 9

Air resistance

(F_AR)