Warm Up List at least 2 things you push List at least 2 things you pull List at least 2 things that fall

Describing Motion Newton’s Laws

First we need to define the word FORCE: The cause of motion (what causes objects to move) Two types of forces Pushes Pulls

Forces are measured in Newtons SI unit of force Symbol: N Measured by using a spring scale

Forces may be balanced or unbalanced Balanced forces – A force that does not change velocity due to its net force being zero. There is NO MOTION → + ← Net Force = 0 2N 2N Forces may be balanced or unbalanced

Unbalanced forces A force that does change velocity due to the two forces being unequal. There is MOTION A NET FORCE → → + ← = Net force = 3N 4N 1N

STAAR 50 N Use the diagram to answer the following question. The arrows below show forces acting on an object. What is the net force on the object and in what direction would the object move? A. 100 N to the right B. 100 N to the left C. 100 N upward D. 150 N upward 100 N 100 N 150 N

STAAR A Jesus, 12N Harder B Jesus, 2N Harder C Marcelo, 10N Harder Marcelo and Jesus are playing tug of war. Marcelo is pulling left on one end of a rope with 10N of force, while Jesus is pulling on the other end of the same rope with 12N of force. Who’s pulling harder? How many Newtons harder is he pulling it? A Jesus, 12N Harder B Jesus, 2N Harder C Marcelo, 10N Harder D Marcelo, 2N Harder

Reflection Are the forces balanced or unbalanced in the picture above? Justify your answer. Report to your captain your findings. Captains will answer for the team.

Speed – how fast on object is going s = d/t Velocity- how fast an object is going in a given direction. V=d/t Acceleration –change in speed or velocity. a= final velocity- initial velocity /time

Newton’s Laws First Law – Inertia Second Law – Acceleration, Force & Mass Third Law – Action-Reaction

First Law Inertia An object at rest [not moving] remains at rest unless acted on by a force [push or pull] An object in motion remains in motion unless acted on by a force [push or pull]

First Law Inertia & Mass Mass is the amount of matter in an object The more MASS an object has, the more INERTIA the object has. Bigger objects are harder to start & stop http://toons.artie.com

Second Law Acceleration & Mass Definitions Acceleration is a change in velocity [speed or direction] Mass is the amount of matter in an object

Second Law Acceleration & Force Acceleration & Mass The more force placed on an object, the more it will accelerate [change its motion] Acceleration & Mass The more mass [or inertia] an object has, the more force it takes to accelerate the object

Third Law Action – Reaction Forces are always produced in pairs with opposite directions & equal strengths For every force there is an equal and opposite force

What about the ladder on top of the truck? The ladder is in motion because the truck is in motion. When the truck stops, the ladder stays in motion. The truck is stopped by the force of the car, but the ladder is not. What force stops the ladder? Gravity.

The truck is in motion. What is the force that causes it to stop? The push of the stopped car. The car is at rest. What is the force that causes it to move? The push of the truck.

Why does the car move [accelerate] when it is hit by the truck? The heavy and moving truck has more force than the small, at rest car. Why does the truck stop moving when it hits the car? The force of the car pushing back on the truck, plus the force of friction between the massive truck and the road slow down, the stop the truck.

The truck is in motion, the car is at rest The truck is in motion, the car is at rest. How do each of these vehicles accelerate? The truck stops moving. The car starts moving. Which one will be the hardest to accelerate? The truck because it has the most mass.

The truck hits the car. An action force stops the truck. What is the equal and opposite reaction force? The force that pushes the car forward.

Newton’s Laws First Law - An object __ _________ Stays ___ ___________ unless acted on by a ___________. An Object ___ ________ stays ___ _______ unless acted on by a ______. Third law - For every ______ there is an _______ and ________ _________.

Bellringer List 2 every day examples for the following: 1. Newtons First Law (Inertia) 2. Newtons Third Law (Action – Reaction)

Bellringer List 2 every day examples for the following: 1. Newtons First Law (Inertia) 2. Newtons Third Law (Action – Reaction)