1. Force
Created by Mrs. Herman
2012

2. Types of Forces
Force – a push or pull on an object in a particular direction (measured in Newtons)
Push in your chair, pull out a drawer, etc.
Contact force – a push or pull on one object by another object that is touching it.
Pressing keys on computer key board, hitting a baseball with a bat, etc.
Noncontact forces – a force that one object can apply to another object without touching it
Gravity, magnetic force, electrical force

3. Forces can affect motion in several ways:
They can make objects start moving, move faster, move slower, stop moving, change direction, change shape
Since force cause change in the speed or direction of an object, we can say that forces cause changes in velocity, so…FORCES CAUSE ACCELERATION!!

5. Balanced vs. Unbalanced Forces
Two or more opposite forces are balanced forces if their effects cancel each other and they do not cause change in an object’s motion.
Unbalanced forces is when one force is stronger then the other and cause a change in motion, speed and /or direction.

6. Gravity
Gravity is an attractive force that exists between all objects that have mass.
Mass is the amount of matter in an object (kg)
Law of Universal Gravitation – all objects are attracted to each other by a gravitational force. The strength of the force depends on the mass of each object and the distance between them.

7. Lesson 1 resources, review, personal tutor: gravity

8. Friction
Static Friction – prevents surfaces from sliding past each other. Up to a limit, the strength of the static friction changes to match the applied force.
Sliding friction – sliding friction opposes the motion of surfaces sliding past each other.
Fluid friction – friction between a surface and a fluid such as water or air.

11. The law says that a thing will keep doing what is doing
The law says that a thing will keep doing what is doing. It will only change when something else makes it change.
This works for things that are not moving. It works for things that are moving. Things that are not moving don’t start moving. Things that are moving keep moving. They move in a straight line with the same speed.
According to Newton’s First Law, if the net force on an object is zero, the motion of the object does not change.