The Force of Friction Date ________
Objects must be acted on by a force to overcome friction.
Friction is the force that opposes motion or the attempted motion of two surfaces that are in contact.
Friction depends on the types of
materials and how much they are
pressed together.
The direction of the friction force is always opposite
to the motion of the object.
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When an object is at rest on a surface it is in _______________.
The net force is _________.
When a small horizontal force is applied to the object, there is a equal friction force exerted in the opposite direction and the object remains at rest.
The force opposing the motion is static friction.
When the applied force exceeds the force of static friction, the object accelerates in the direction of the net force.
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As the applied force increases, so does the static friction force. When the applied force is greater than the static friction force the object moves.
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Static Friction
On the surface of all objects there are tiny bumps and
ridges that catch on each other when two objects are moving past each other.
If you try to slide the object with a small force and the
object doesn't move, the force of friction is equal to the applied force.
This is static friction.
Sliding Friction
If you apply a little more force and the object starts to
move, the force opposing the motion of the object while
it is still moving is sliding friction.
Sliding friction opposes motion less than static friction.
Sliding friction depends on the type of materials in contact and the weight
of the object.
Name an example when you have noticed the difference between static friction is and sliding friction
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Rolling Friction
Rolling friction is the force that opposes the
motion of a round object rolled along a flat surface.
Fluid Friction
Fluid friction is the force that opposes the motion of an object in a fluid (liquid or gas).
Fluid friction depends on the _____________ ______________ __________ of the object, and the ________________ of the object in the fluid.
What do you feel when you stick you hand out of the window of a fast moving car?
Friction Assignment
Pick any sport besides baseball or softball.
Write a story about what would happen in that sport without friction on the field.
As in the Magic School Bus video, the friction was only on the field so the players were able to throw and catch the ball.
Due ______________________
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