Force, Mass, & Acceleration

#1 Sir Isaac Newton Lived in England from 1642 to 1727 Physicist & mathematician Formulated the basic laws of mechanics (motion) Discovered the universal law of gravitation Invented calculus (math used to solve physics problems) Before he was 30 years old

Newton’s Laws A Short Biography Elements of Physics: Motion, Force, and Gravity. United Learning. 2003. unitedstreaming. 3 October 2005 <http://www.unitedstreaming.com/>

Newton’s Laws of Motion In the actual words: First Law: An object at rest will remain at rest unless acted on by an unbalanced force. An object in motion will remain in motion with constant speed and direction unless acted on by an unbalanced force.

1st law = INERTIA Newton’s 1st Law is also known as the law of inertia. Inertia is the property of an object to resist changing its state of motion. The amount of inertia depends on the mass of the object. Let's take a closer look at inertia Newton's Laws videos!

INERTIA An object with more mass has more inertia, or more resistance to changes in motion an object with less mass has less inertia, or less resistance to change in motion

DEMO TIME!!! Watch as the book stays on the table even though the paper moves! How does this show inertia?

Newton’s Laws of Motion Second Law: When there is a force acting on an object, it will move in the direction of the force: force increases acceleration mass resists acceleration

Newton’s Laws of Motion Second Law: The acceleration of an object is directly proportional to the force acting on it and inversely proportional to its mass. Acceleration a = F Force (N) (m/s2) m mass (kg)

2nd Law Three things you can get from the equation: Let's Watch the second Law Video!! Three things you can get from the equation: Force (newtons) causes acceleration. Mass (kg) resists acceleration. The acceleration(m/s2) you get is equal to the ratio of force over mass.

DEMO TIME Volunteer to sit in the chair? Watch as the volunteer moves in the direction of my force? How does this relate to law 2?

LAW 3 What does Newton's 3rd law say?? Video Third Law: For every action force, there is an equal and opposite reaction force. If you push off on the wall The wall will exert an equal and opposite force on you What does Newton's 3rd law say?? Video

DEMO TIME!! Another volunteer?? This time they will push themselves. Which way did they move… opposite of the force or in the same direction of their force? How does this relate to law 3?

Try to match the motion with the correct law. Group ACTIVITY!!! Try to match the motion with the correct law.

What is a FORCE? A force is a push or a pull, or any action that has the ability to change motion. Examples: Contraction (pulling) of muscles that make bones move pushing a grocery cart lifting your backpack. Force Video

What is the difference between Force & Weight Force is a push or a pull that can change the motion of an object. It is measured in Newtons. Weight is the force caused by Earth’s gravity that acts on the mass of an object. It is measured in Newtons.

How are Force and Mass related? Force is a push or a pull that can change the motion of an object. It is created when a mass is accelerated by something like gravity Mass is the amount of matter (stuff) in an object mass is a basic property of all objects mass resists the action of forces by making objects harder to accelerate.

What is the difference between Mass & Weight Mass is the amount of matter (stuff) in an object Mass is the same everywhere in the universe – it does not change Weight is the force of Earth’s gravity acting on the mass of an object. Weight can change at different places in the universe depending on the gravity

Balanced forces When the forces on an object are balanced, the force in one direction exactly matches the force in the opposite direction

Unbalanced forces forces are unbalanced when the force acting in one direction is greater than the force acting in another direction.

Equilibrium An object is in equilibrium when the forces acting on it are balanced, the net force is zero, and there is no change in motion.

NET FORCE The net force is the sum of all the forces acting on an object. The net force on an object that is not moving is zero. This means that the forces acting on the object are balanced the motion is not changing NO acceleration is occurring.

REFLECTION QUESTIONS Describe each of Newton’s 3 laws of motion 1lb = ______ newtons? F= ? (equation?) Give the units for force and acceleration What happens when something is at equilibrium? What is a Net force?

Conversion from pounds to newtons One pound is equal to 4.48 newtons. Your weight in pounds = ______ lbs. x 4.48N/1lb. ______ N (your weight in newtons.)