This week’s focus:
Friction
Prior to the
video, complete the anticipation guide on types of friction:
Notes on Friction:
FORCE
A push or pull is called a force. Force may give energy to an object, causing
it to charge direction, to stop moving or to start moving.
An example of a force that occurs in
nature is gravity. Gravity pulls you to
the ground. A force that is applied by a
machine could be a car. The engine moves
the car when you apply pressure to the gas pedal. A force that is applied by you would be running. You are pushing against the ground as you
run.
FRICTION
The force that opposes the motion of
an object would be called friction.
Friction occurs when two objects are in contract with each other and
moving against one another. Three kinds
of friction are sliding friction, rolling friction, and fluid friction.
Sliding
friction occurs anytime that there are two solid surfaces sliding over each
other in the opposite direction. The
three factors that cause sliding friction are weight, type of surface
(texture), and the amount of the surface (area).
Rolling
friction occurs when an object rolls over a surface. Comparing sliding friction to rolling
friction, sliding friction is greater than rolling friction because there is a
smaller friction area.
Fluid
friction occurs when an object moves through a fluid. Fluid is any liquid or gas. Oil, water or lotions are examples of
this. Lubricants are substances the
change sliding friction to fluid friction by means of oil or greases. Friction is not always harmful! Sometimes it
can be helpful when it stops the motion.
BALANCED AND
UNBALANCED FORCES
Balanced forces are forces acting in opposite directions that
are equal, they cancel each other out.
There is no motion between forces that are balanced. Balanced forces do not cause a change in
motion, therefore if there is motion nothing is being done to it. So this would
keep an object at constant velocity.
5N ────→
=
0 N
←──── 5N
Unbalanced
forces are not equal forces acting in opposite directions or equal and unequal
forces acting in the same direction. The
net result of unbalanced forces that are opposing is that the movement goes in
the direction of the larger force. In
the event of unbalanced forces that are in the same direction the net result is
that they would add together.
10N ─────→
= ───→5N
←─── 5N
OR
10N ────→
=
───────→ 20N
10N
────→
Homework:
Friction Reading Sheet
Friction Lab
Homework: CK-12 Types of Friction: Was due by
Friday, extended until Monday 10/24
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