Bell Work Week of Monday, March 23 – Friday, March 27 Thursday, March 26 Who is attributed with the discovery of the three Laws of Motion?

What’s Happening in AG? Thurs. 3/26 Announcements Due Today – Newton’s Laws Webquest Vocab Quiz – Friday, March 27 (TOMORROW) FFA Meeting – Thursday, April 1 Greenhand Degree Applications, Chapter Degree Applications, and 2015-2016 Officer Applications will be available What are we doing today? Lecture – Review Newton’s Laws

Newton’s Laws of Motion Review Intro to Agriculture AAEC – Paradise Valley Spring 2015

Background Sir Isaac Newton (1643-1727) an English scientist and mathematician famous for his discovery of the law of gravity also discovered the three laws of motion. He published them in his book Philosophiae Naturalis Principia Mathematica (mathematic principles of natural philosophy) in 1687. Today these laws are known as Newton’s Laws of Motion and describe the motion of all objects on the scale we experience in our everyday lives.

“If I have ever made any valuable discoveries, it has been owing more to patient attention, than to any other talent.” -Sir Isaac Newton

Newton’s Laws of Motion An object in motion tends to stay in motion and an object at rest tends to stay at rest unless acted upon by an unbalanced force. Force equals mass times acceleration (F = ma). For every action there is an equal and opposite reaction.

Newton’s First Law An object at rest tends to stay at rest and an object in motion tends to stay in motion unless acted upon by an unbalanced force.

What does this mean? Basically, an object will “keep doing what it was doing” unless acted on by an unbalanced force. If the object was sitting still, it will remain stationary. If it was moving at a constant velocity, it will keep moving. It takes force to change the motion of an object.

Balanced Forces Balanced Forces = forces that are equal in size and in opposite directions (no movement occurs)

Unbalanced Forces Unbalanced Forces = the two forces are not equal, so that there is a movement in one direction.  

Newton’s First Law is also called the Law of Inertia Inertia: the tendency of an object to resist changes in its state of motion The First Law states that all objects have inertia. The more mass an object has, the more inertia it has (and the harder it is to change its motion).

Jenga is a game based on inertia Jenga is a game based on inertia.  You try to move the blocks without moving the other blocks. Eventually, the tower becomes unbalanced. 

Force equals mass times acceleration. F = ma Newton’s Second Law Force equals mass times acceleration. F = ma Acceleration: a measurement of how quickly an object is changing speed.

What does this mean? F = ma basically means that the force of an object comes from its mass and its acceleration. Something very massive (high mass) that’s changing speed very slowly (low acceleration), like a glacier, can still have great force. Something very small (low mass) that’s changing speed very quickly (high acceleration), like a bullet, can still have a great force. Something very small changing speed very slowly will have a very weak force.

F = MA Practice Problems If you push an object that has a mass of 2 kg, and the net force acting on the object is 6N, what is the object's acceleration?  If a mass of 5kg is moving at an acceleration of 3 m/s2, what is the force?

In outer space, away from gravity and any sources of friction, a rocket ship launched with a certain speed and direction would keep going in that same direction and at that same speed forever.

What is Gravity? Gravity = the attractive force between two objects; depends on mass and distance Earth’s Gravity 9.80665 m / s2 Moon’s Gravity 1.622 m/s²

For every action there is an equal and opposite reaction. Newton’s Third Law For every action there is an equal and opposite reaction.

What does this mean? For every force acting on an object, there is an equal force acting in the opposite direction. Right now, gravity is pulling you down in your seat, but Newton’s Third Law says your seat is pushing up against you with equal force. This is why you are not moving. There is a balanced force acting on you– gravity pulling down, your seat pushing up.

P = MV Momentum Momentum describes how much force is necessary to change an objects motion. Which has more momentum: soccer ball traveling at 5 m/s   a train traveling at 5 m/s

P = MV Practice Problems 1. What is the momentum of a car with a mass of 1000 kg traveling at the speed of 2 m/s? 2.  A baseball has a momentum of 6 kg*m/s.  If the mass of the baseball is 3 kg, what is the baseball's velocity? 3.  What is the mass of a person walking at a speed of 2 m/s if the person's momentum is 50 kg*m/s

Vocabulary Check Inertia: the tendency of an object to resist changes in its state of motion Acceleration: a change in velocity; a measurement of how quickly an object is changing speed, direction or both Velocity: The rate of change of a position along a straight line with respect to time Force: strength or energy