Newton’s Laws

Sir Isaac Newton

An object at rest will stay at rest. An object in motion stays in motion with the same speed and direction unless acted upon by an unbalanced force.The acceleration of an object is dependent upon two variables. The net force acting upon the object and the mass of the object.For every action there is an equal and opposite reaction.

Newton’s First Law

An object at rest will stay at rest. An object in motion stays in motion with the same speed and direction unless acted upon by an unbalanced force. For additional information visit:

http://www.physicsclassroom.com/mmedia/newtlaws/cci.html

Newton’s First Law Examples

•To dislodge ketchup from the bottom of a ketchup bottle, it is often turned upside down and thrust downward at high speeds and then abruptly halted.

•Headrests are placed in cars to prevent whiplash injuries during rear-end collisions.

•While riding a skateboard (or wagon or bicycle), you fly forward off the board when hitting a curb or rock or other object that abruptly halts the motion of the skateboard.

• Can you think of more???

 

Newton’s First Law

Watch This!

Newton’s Second Law

For additional information visit:

http://www.physicsclassroom.com/mmedia/newtlaws/efff.html

Newton's second law states that the acceleration of an object is directly related to the net force and inversely related to its mass.

ForceAcceleration =

Mass

Newton’s Second Law

If the elephant weighs more and experiences a greater downwards pull

of gravity compared to the feather, why then does it hit the ground at the

same time as the feather?

2nd Law Explained

Remember the second law - the acceleration of an object is directly related to the net force and inversely related to its mass. When figuring the acceleration of object, there are two factors to consider - force and mass. The elephant experiences a much greater force which will produce larger accelerations. BUT the mass of an object resists acceleration. Thus, the greater mass of the elephant offsets the influence of the greater force. It is the force/mass ratio which determines the acceleration.

Newton’s Second Law

Watch this!

Newton’s Third Law

For every actionthere is an equal and opposite reaction.

For additional information visit: http://www.allstar.fiu.edu/aerojava/rocket1a.htm

Newton’s Third Law

Watch This!

Quick DemonstrationTry this:

•Press the side of your hand against the edge of a table. Notice how your hand becomes distorted. •Clearly, a force is being exerted on it. You can see the edge of the desk pressing into your hand; you can feel the desk exerting a force on your hand. •Now press harder. The harder you press the harder the desk pushes back on your hand. •Remember this important point: You can only feel the forces being exerted on you, not the forces you exert on something else. So, it is the force the desk is exerting on you that you see and feel in your hand.

Law application

Bob the Beaker hit a rock while moving on his skateboard.

He tumbled and broke.

Which law of physics applies to this situation?

Newton’s 1st Law

Newton’s 2nd Law

Newton’s 3rd Law

Why Newton’s 1st Law?

Bob the beaker is traveling 10 miles an hour on his skateboard and being in motion, he wants to stay in motion. When his skateboard stops due to the rock, Bob still wants to carry on the motion and he falls.

An object in motion stays in motion with the same speed and direction unless acted upon by an unbalanced force.

Law applicationDuring the 9th inning of the World Series, New York Yankee Roger Clemens pitches the ball and Atlanta Brave Kevin Millwood hits the ball out of the park for a homerun.

Which law of physics applies to this situation?

Newton’s 1st Law

Newton’s 2nd Law

Newton’s 3rd Law

Why Newton’s 3rd Law?

Clemmons’ baseball forces Millwood’s bat to the right (an action) when they meet; the bat forces the ball to the left (the reaction).For every action there

is an equal and opposite reaction.

Law applicationYou are helping rearrange your living room furniture. You push with all you strength and easily move the chair to it’s new spot in the corner. You then push with all you might to move the couch to it’s new spot but it barely moves. Which law of physics applies to this situation?

Newton’s 1st Law

Newton’s 2nd Law

Newton’s 3rd Law

Why Newton’s 2nd law?Newton’s 2nd law of motion states that

acceleration depends on two factors – force & mass.

Acceleration = Force / Mass.

This means the mass of an object has a negative effect on acceleration. Simply put if an object

has more mass it will be harder to move.(force has a positive relationship; more force more acceleration)