Motion & Forces
Jan 17, 2016
Motion & Forces
Force• A push or
a pull*Cause an
object to start moving, stop moving, or change direction
Unbalanced Force
• Cause an object to start moving, stop moving, or change directions
• Unbalanced forces will change an object’s motion
Unbalanced ForcesNet Force = the overall
force on an object after all the forces on an object are added up
1 2 1
1 2 1
3
12
Balanced Forces• Equal forces
acting on each other in opposite directions
*Balanced forces acting on an object will not change the objects motion
1 0 1
1 0 1
An object at rest will remain at rest and an object that is moving at a constant velocity will remain at a constant velocity unlessacted upon by an unbalanced force.
Inertia-the tendency of an objectto resist change in its motion.Newton’s 1st Law of Motion is also called the Law of Inertia.
Inertia• Force is needed to
change the motion of an object. Every object resists any change to its motion. This change is called inertia. The tendency of an object to resist change in its motion
Ex. If you are not wearing a seat belt when a car crashes inertia continues to carry you forward
What affects Inertia?
• Mass the greater the mass the greater the inertia
Question what has greater inertia a Honda Civic going 30 k/ph, or a Truck at the same speed?
““Friction””The force that one surface exerts on another when
the two rub against each other.
Depends on 2 factors
1) The two surfaces involved
2) How hard are the surfaces pushing against each other
Types of Friction
• Sliding – when solids slide over each other
• Rolling - when an object rolls over a surface
• Fluid- objects moving through fluids (liquid or gases)
Weight vs. Mass• Weight is a measure
of the force of gravity on an object, mass is a measure of the amount of matter in an object
• You have the same mass on the Moon as Earth, but different weights
Gravity
• Gravity is a force between any two objects, the force of gravity is related to the mass of the objects, and their distance from each other
Force in Fluids
• Force is applied to a fluid causing pressure increase in a fluid
• The heart applies pressure to the blood forcing it through your vessels, blood flow in the body requires force