1. The frictional force between two surfaces in contact depends on: a. whether a lubricant is used or not. b. the types

[answerhappygod]

1. The frictional force between two surfaces in contact
depends on:
a. whether a lubricant is used or not.
b. the types of materials.
c. all of the previous choices.
d. the normal force pressing one against the other.
2. Are the normal force and the force of gravity on an object on
a surface always equal in magnitude? Explain
3. Friction can be your best friend or your worst
enemy. Describe a situation where friction is helpful in your
daily life and a situation where friction is not helpful.