1. 14 Force & Motion
Mr. Perez

2. Important Vocabulary Gravitation Force Balanced forces
Unbalanced forces
Inertia
Contact force
Friction
Non-contact force
Gravity

3. What is a force?
A force is a push or a pull exerted by one object on another object.
Forces have both a size (strength) and a direction (like velocity and acceleration).
Newtons (N): strength of a force of an object
Ex: One Newton is the force required to lift a quarter-pound hamburger

4. Contact Forces
Contact forces are forces exerted only when two objects are touching each other
Applied force: force put on an object by another object
Friction is a force that opposes the relative motion of two objects that are in contact (Smooth surfaces have smaller friction forces than rough surfaces)
Air resistance is a force exerted by air on an object moving in the air
Buoyant force is the upward force exerted by a fluid that opposes the immersed weight of an object
Normal force: The normal force is the support force exerted upon an object that is in contact with another stable object.

5. Non-contact Forces
Non-contact forces are forces exerted by one object on another when the objects are NOT touching
gravitational force: force that pulls objects towards each other
law of universal Gravitation: force of gravity acts between all objects in the universe that have mass
any 2 objects in the universe that have mass are attracted to each other
Electrical force: force between 2 charged objects
Magnetic force: the attraction or repulsion between magnetic poles

7. Gravitational Force

8. Videos https://www.youtube.com/watch?v=tEIhHwizrmQ
ar-system/sgravity-and-inertia.htm
ces-and-motion/force-and-motion.htm

9. Mass and Weight Mass and weight are two different measurements
Mass is the amount of matter in you
Measured in kilograms (kg)
Does not change depending where you are
Weight is the strength of gravitational force that Earth exerts on you
Measured in Newtons (N)
We usually measure weight in pounds (lbs.) (1 lb = 4.4 N)
Changes depending where you are

10. Videos
T8RouhPA

11. Inertia Objects resist having their motion changed
Inertia is the tendency of an object to resist a change in its motion
Inertia is the reason why an object at rest tends to stay at rest (Newton’s First Law of Motion)
Inertia causes moving objects to move in a straight line at a constant speed
The more mass an object has, the more inertia it has

12. Inertia

13. Combining Forces
When more than one force acts on an object, they combine.
The combination of all the forces acting on an object is called the net force
When the forces on an object are in the same direction, they are added together
When two forces on an object are in opposite directions, the net force equals the larger force minus the smaller force

15. Balanced and Unbalanced Forces
When the net force on an object equals zero, the forces are balanced
When the net force on object is NOT zero, the forces are unbalanced
20 N Right
20 N Left

16. Balanced and Unbalanced Forces
Balances forces cause an object to stay where they are.
Unbalanced forces causes an object to move (or stop moving)
The speed of an object can change
The direction an object is moving can change

17. Links

18. References Google Images
Florida Science Grade 6, Glencoe Science & McGraw Hill Publishing