Chapter 12

Chapter 12.2 Newton’s 1st and 2nd Laws NotesName ___________________________ Per. ____

Mrs. Zeiders

Newton’s First Law

· Objects in motion tend to ___________________________, objects at rest tend to stay at rest unless…either is acted upon by an unbalanced force.

· The state of motion (resting or moving) doesn’t change unless acted upon by an ___________________________________.

· Also known as the “____________________________”

Force or Free Body Diagrams

Free-body diagrams are diagrams used to show the relative magnitude and direction of all forces acting upon an object in a given situation

· The _________________________of the arrow in a free body diagram reflects the ______________________ of the force. The direction of the arrow shows the direction that the force is acting.

· Unbalanced forces…IF either all the vertical forces (up and down) do not cancel each other out and/or all horizontal forces do not cancel each other, THEN … ____________________________________________

______________________________________________________________________________________________

Steps to making your own Free Body Diagrams:

· Identify the object you will draw a diagram for. 

· Identify all the forces acting directly on the object and the object exerting them. 

· Draw a box to represent the object.

· Draw a vector to represent each force.  Draw it in the direction the force is being exerted, and label it by (a) the type of force, (b) the object exerting the force, and (c) the object receiving the force (which will be you object of interest).  It will have the form F(type)exerting object -> object of interest

· If the object is stationary or is moving at a constant velocity, the vectors should add up to zero.  If the object is accelerating, the sum of the vectors should produce a vector in the same direction as the acceleration.

Examples:

A sky diver is falling at a constant velocity.

A car is driving down the road and accelerating.

Newton’s Second Law

· In general, more _________________ will mean more acceleration (throw harder)

· More ____________________ will lead to less acceleration (throwing a heavy object)

· Can also be rearranged to be written to find the Net Force

Chapter 12.3 Newton’s 3rd Law and Momentum Notes

Newton’s 3rd Law

· Whenever an object exerts a force on a second object, the second object exerts an ___________________________ force on the first object.

· These are known as _______________________________

· Ex: Swimmer in water pushes against water, forcing the water to move in that direction. The water exerts an equal force upon the swimmer, pushing her through the water.

· Not all action and reaction forces result in ____________________________.

· Ex: Pushing against a wall is an action force, the wall exerts an equal and opposite force against your hand, but neither you or the wall move.

(Pm • v)Momentum

· Product (multiply) of an object’s mass and velocity. P = m•v

· Units for P= _____________________ ____________

· Units for m= ____________________ _____________

· Units for v= _____________________ _____________

Conservation of Momentum

· In a ___________ _____________ momentum is conserved.

· If no net force acts on a system, then the total momentum of the system does not change. If one object _____________ momentum, another _____________ momentum. Momentum is ________________ overall.