Download Forces

Forces
Calculating Force and Types of Friction
Force: A push or pull exerted on an object
• A force is described by its strength and by the
direction in which it acts
• SI Unit of Force = newton (N)
Sir Isaac Newton
Net Force: Sum of all forces acting on an object
• The change in motion of an object is determined
by the net force
• You can find the net force by adding together the
strengths of all the individual forces
• Any nonzero net force causes a change in motion
Calculating Net Force:
Example:
2 forces pushing on an object from the right
5N
3N
8N
Net Force = 8N moving the box to the Right
What is the net force for each situation?
State whether the forces are Balanced or Unbalanced
What about this situation?
Balanced Forces:
• result in no movement of
the object
Unbalanced Forces:
• the object will move in
the direction with the
larger applied force
Friction: The force that two surfaces exert on
each other when they rub together
• Two factors that affect the force of friction
1. The surfaces involved
2. How hard the surfaces are pushed together
• Smooth surfaces produce less friction
•Friction acts in the direction opposite of
the object’s motion
Types of Friction
1. Sliding: when 2 solid surfaces slide over each other
* Makes moving objects slow down or stop
2. Static: acts on objects that are NOT moving
* Force that keeps you from moving
3. Fluid: when a solid object moves through Water or Air
4. Rolling: occurs when an object Rolls across a surface
Gravity: the force that acts to pull objects straight
down toward the center of the earth
Universal Gravitation: states that ALL objects are
attracted to each other
2 factors that affect Gravitational Attraction
* Mass and the Distance between the objects
• The greater the mass, the great the gravitational force
• As distance increases, gravitational force decreases
Calculating Force:
F = ma
Force = mass X acceleration
This formula calculates the amount of force that
must be applied to an object to accelerate it