Ch4_solomonk

**Summary of Newton's Laws Lesson 1 a-dtoc**
a - Newton's First Law of Motion What is Newton's first law of motion? What are applications of Newton's first law of motion?
 * sometimes referred to as the law of inertia
 * states: an object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force
 * all objects resist changes in their state of motion
 * when a car brakes, there is no unbalanced force to change your own state of motion
 * you will continue in motion and slide forward in your seat

b - Inertia and Mass What is inertia? Who is Galileo and what did he have to do with the concepts explained? What effects to forces have on objects? How does mass affect inertia?
 * the natural tendency of objects to resist changes in their state of motion
 * the resistance an object has to a change in its state of motion
 * premier scientist in the 17th century
 * developed the concept of inertia
 * figured out that moving objects eventually stop because of the force of friciton
 * forces do not keep objects moving
 * forces are what bring objects to rest
 * the more inertia that an object has, the more mass it has
 * a more massive object has a greater tendency to resist changes in its state of motion

c - state of motion What is state of motion?
 * the state of motion of an object is defined by its velocity
 * inertia redefined:
 * the tendency of an object to resist changes in its velocity
 * tendency of an object to resist accelerations

d - balanced and unbalanced forces What is an unbalanced force? What is meant if a force is balanced? How is it determined if a force is balanced or unbalanced?
 * not at equilibrium
 * unbalanced forces cause acceleration
 * when an object changes its state of motion
 * forces of an equal magnitude in opposite directions
 * said to be at equilibrium
 * first determine what forces are acting upon the object and in what direction
 * balanced if 2 individual forces are of equal magnitude and in opposite directions
 * unbalanced when there is an individual force that is not being balanced by anything

**Inertia Class Notes 11/15/11**
__**first law of motion:**__ - an object isn't going to change unless something forces it to - it will go constant speed in a straight line - no change in motion unless an unbalanced force acts on the object...otherwise it will move at constant speed in a straight line - Galileo came up with the law of inertia, but Newton incorporated it into his laws - inertia is a property that measures how difficult it is to change an object's motion - this is mass (kg) - weight is a force (N) - the pull of gravity on a mass - g=9.8m/s/s - weight = mass x gravity - w=(m)(g) __balanced forces:__ - forces have the same magnitude in opposite directions - equilibrium: - static - at rest, no motion - dynamic - constant speed - when an unbalanced force acts on an object, it will accelerate in the direction of the unbalanced force - ex: if normal is greater than weight N>W, an object will accelerate up - speeding up going up - increasing speed up - slowing down going down - decreasing speed down - ex: diving into pool - ex: going down in elevator - net force: sigmaF (sum of all the forces)
 * __second law of motion:__**

** Summary of Newton's Laws Lesson 2 a-d **
a - the meaning of force What is a force? What is a contact force? What is an action-at-a-distance force?
 * a force is a push or a pull upon an object resulting from the object's interaction with another object
 * forces only exist as a result of an interaction
 * a force is a vector quantity
 * types of forces that result when the two interacting objects are perceived to be physically contacting each other
 * ex: frictional, tension, normal, air resistance, applied, spring
 * types of forces that result even when the two interacting objects are not in physical contact with each other, yet are able to exert a push or pull despite their separation
 * ex: gravitational
 * electrical
 * magnetic

b - types of forces What are the types of forces? What is the difference between mass and weight?
 * applied force - applied to an object by a person or another object
 * gravity force (weight) - all object upon earth experience a force of gravity that is directed downward towards the center of the earth
 * normal - support force exerted upon an object that is in contact with another stable object
 * friction - exerted by a surface as an object moves across it or makes an effort to move across it - there are sliding and static
 * air resistance - acts upon objects as they travel through the air. often observed to oppose the motion of an object
 * tension - transmitted through a string, rope, cable, or wire when it is pulled tight by forces acting from opposite ends
 * spring - force exerted by a compressed or stretched spring upon any object that is attached to it
 * mass - the amound of matter that is contained by the object
 * weight - the force of gravity acting upon an object

c - drawing free-body diagrams What are free body-diagrams used for and how do they depict the idea?
 * used to show the relative magnitude and direction of all forces acting upon an object in a given situation
 * size of arrow reflects magnitude of force
 * direction of arrow shows directing that the force is acting
 * can depict 4 forces

d - determining the net force What is a net force?
 * the vector sum of all the forces that act upon an object
 * when there is an unbalanced force

**Summary of Newton's Laws Lesson 2 a-b**
a - Newton's Second Law What is Newton's Second Law of motion? What is net force?
 * pertains to the behavior of objects for which all existing forces are not balanced
 * states that the acceleration of an object is dependent upon two variables
 * the net force acting upon the object
 * mass of the object
 * the acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object
 * net force = (mass)(acceleration)
 * acceleration is directly proportional to the net force

b - the big misconception What are some common misunderstandings about Newton's laws of motion?
 * not true: the idea that sustaining motion requires a continued force
 * for real: it is that a net force (an unbalanced force) causes an acceleration
 * for real: the law declares that a force is not needed to keep an object in motion

****Summary of Newton's Laws Lesson 3****
Net Force Problems Revisited
 * force directed at an angle can be divided into a horizontal and a vertical component
 * components replace the original force
 * net forces can be determined by adding all the forces as vectors
 * acceleration can be determined as the ratio of Fnet/mass