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Forces and Newton. 1. Forces. A force is a push or a pull . Force is measured in Newtons. pull. push. Exerting a force on an object causes its motion to change. So, a force causes an object to accelerate. For Example….
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1. Forces • A force is a push or a pull. • Force is measured in Newtons. pull push
Exerting a force on an object causes its motion to change. • So, a force causes an object to accelerate.
For Example… • When you throw a ball, your hand exerts a force on the ball, causing it to speed up. • The ball has an acceleration because the speed of the ball has increased.
2. Balanced and Unbalanced Forces
Two or more forces are balanced forces if their effects cancel each other out.
If the effects of the forces don’t cancel each other, the forces areunbalanced forces.
3. Combining Forces • When more than one force acts on an object, the forces combine. • The combination of all forces is the NET FORCE.
If the forces are in the same direction, they add together to form the Net Force. net force
If two forces are in opposite directions, the net force is the difference between the two forces .
1. 2. 3. 4. 5. 6.
Individual practice: Calculating Net Force
4. Newton's Laws of Motion • There are 3 Laws of Motion discovered by Sir Isaac Newton. • Newton’s First Law • Newton’s Second Law • Newton’s Third Law 1643 - 1727
Newton’s First Law of Motion • An object at rest will remain at rest OR • An object moving will continue moving • UNTIL a FORCE acts on it.
Examples of Newton’s 1st Law: 1. A book on a table will remain at rest until a force acts on it. Reaction force of table Weight of book
A thrown football (moving object) will continue moving until a force acts on it to make it stop. • Q1. Why does the football stop? • Q2. What force makes it stop?
This lady is able to pull the tablecloth off the table without moving the dishes. • Newton’s First Law = Law of INERTIA You try: cup/penny/notecard
Newton's Second Law • An object that has a force acting on it will accelerate in the direction of the force.
Force = Mass x Acceleration Q1.Which one will hit the ground with the greatest force? F = m x a If MASS is larger, then force becomes larger
F = m x a Q1. Which boy will kick the ball farther? Jason Jeremy Higher KICK FORCE = Higher ACCELERATION = Ball goes farther!
Newton's Third Law • Forces always occur in equal but opposite pairs. • Every ACTION has an equal and opposite REACTION.
Pushing on a wall • Example of Newton’s Third Law:
For every action, there is an equal and opposite reaction. Newton’s Third Law of Motion
Another example of Action -Reaction Forces You Try: Balloon Rockets
YEA! We are finished!