Friction And Force Flashcards
What are two things all forces have?
Size and direction
What is a force?
Push or pull
What unit is a force measured in?
Newtons (N)
What are some examples of a force?
Opening a book with your fingers and sitting in a chair
Forces can be _______ and ___________.
Seen and unseen
What is net force?
the force that results from combining all the forces exerted on an object.
How do you find net force?
Add together the forces moving in the same direction
How do you find net force when forces are in different directions?
Subtract the smaller force from the larger force
When is the force on an object unbalanced?
When the net force is a number other than zero
What causes a change in motion (acceleration) ?
Unbalanced forces
What are unbalanced forces necessary for?
To change the motion of moving objects
When are e forces on an object balanced?
When the force produces a net force of zero
Hat do balanced forces not do?
They do not change the motion of a moving object or cause a nonmoving object to start moving
What is friction?
a force that opposes motion between two surfaces that are touching
Where does friction occur?
Friction occurs between the surface of an object that is rough. Even surfaces that look or feel smooth are covered with microscopic hills and valleys.
The friction between two surfaces includes what?
roughness of the surfaces and the force pushing the surfaces together.
The rougher the surface……
The rougher the surface the greater the friction. Smoother surfaces have less friction.
The amount if friction depend on what?
The force pushing the surfaces together
What happens when the force pushing the surfaces together increases?
the hills and valleys of the surfaces can come into closer contact. This causes friction to increase.
_______ objects exert less force than ______ objects do
Less massive/ massive
What is sliding friction?
the friction you observe when you are sliding objects.
What is rolling friction?
the friction between wheels and the floor when rolling an object.
Does rolling or sliding friction exert more friction?
Sliding
Rolling friction is an important part of….
All means of transportation
What is fluid friction?
friction between an object and water. Fluid friction opposes the motion of objects moving through.
What is static friction?
when. A force is applied to an object but does not cause the object to move. The force does not move because the force of static friction balances the force applied. Static friction disappears as soon as an object starts moving and then another type of friction occurs.
How can friction cause problems?
Friction causes problems between moving engine parts increasing their temperature and causing parts to wear down. Liquid coolant must be added. It also puts holes in your pants and socks
Friction by wind and water causes…
Erosion
What are 3 ways to decrease friction?
Applying a lubricant to surfaces can reduce friction.
Using sliding instead of rolling. For example, ball bearings are placed between the wheels and axles of skates and bicycles.
Make rough surfaces smoother.
What are 2 ways to increase friction?
Make surfaces rougher. Ex: sand scattered on icy roads keeps cars form skidding.
Increase the force pushing the surfaces together. Ex: putting a heavy rock on a magazine to keep it from blowing away outside.