7. Types of FRICTION (forces)
Friction is a force, measured in newtons just like any other
force.
Static friction keeps an object at rest from moving.
Sliding friction is a force that resists the motion of an object
moving across a surface.
Rolling friction is the friction exerted when an object rolls
over a surface.
Static friction
Sliding friction Rolling friction
8. FACTORS AFFECTING FRICTION
Friction depends on a material’s properties such as roughness,
how clean the surfaces are, and other factors.
Friction depends upon two factors.
Nature of the surfaces in contact. (The smoothness of the surfaces).
How hard the surfaces press together.
Friction is less on a smooth surface.
Friction is more on a rough surface
9. Reducing friction
Friction can be reduced by :-
•Using lubricants like powders or oils and grease.
•Using rollers or wheels.
•Using ball bearings
13. 2. Which of the following does not
involve any friction?
a) A bicycle rolling down a hill
b) baseball player sliding into 2nd
base
c) A diver falling through the air to
a pool
d) All of the above experience some
friction.
14. 3. An example of rolling friction is
a)using oil to lubricate
b)wheels on your skateboard
c)dragging your sister across the
floor on a blanket
d)the little mermaid swimming
through the ocean
15. 4. Why is it easy to slip when there is water on the
floor?
a) The water is a lubricant and reduces the friction
between your feet and the floor.
b) The friction between your feet and the floor
changes from kinetic to static friction.
c) The water increases the friction between your
feet and the floor.
d) The friction between our feet and the floor
changes from sliding kinetic friction to rolling
kinetic friction.
16. 5. Which surface will produce
the least amount of friction?
a) gravel running track
b) smooth glass tabletop
c) grassy soccer field
