Ch4_RubensteinD

= = toc =Newton's Laws=

__Homework 11/14/11 Newton's Laws Lesson 1 (a-d)__
- Newton's first law is the law of inertia - Can often be stated as: An object at rest stays at rest and an object in motion stays in motion with the same speed and int he same direction unless acted upon by an unbalanced force - An object at rest will stay at rest and an object in motion will stay in motion - An object will only change if something forces it to "the lazy law" - No change in motion unless an unbalanced force acts on the object... otherwise move at constant speed in a straight line - Ex: experiences in an automobile; the car will stay in motion while no unbalanced forces are acting upon it - Inertia is the tendency of objects to resist changes in their state of motion - Inertia itself is a property of matter - Inertia is a property that measures how difficult it is to change an object's motion - Newton said that a force is NOT needed to keep an object in motion - It is the presence of a force that causes an object to come to rest, not the absence of a force - The tendency of an object to resist changes in its state of motion varies with mass - Mass is the quantity that is solely dependent upon the inertia of an object - Used to tell you how much inertia something has - The state of motion of an object is defined by its velocity - Inertia is the tendency of an object to resist changes in its velocity AND the tendency of an object to resist accelerations - A BALANCED force are two forces that are at equilibrium, so they are not changing the object's state of motion at all - An UNBALANCED force are when two forces are acting upon an object and one is greater than the other, causing the object to change its current state of motion - Unbalanced forces cause accelerations
 * Part A **
 * What is Newton's first law of motion?**
 * How can Newton's first law be applied to everyday life?**
 * This part basically describes Newton's first law and gives examples of how this law applies to the everyday life of a person. Newton's first law states that an object at rest will stay at rest and an object in motion will stay in motion. Also, it can be applied to everyday life in the situation of a car/seatbelt. If the car was acted upon by an unbalanced force then the seatbelt would be used as the unbalanced force that would stop the person from remaining in motion.
 * Part B **
 * How does inertia apply to Newton's first law? **
 * How did Newton add on to Galileo's idea?**
 * What does mass have to do with inertia? **
 * This part explains how inertia applies to Newton's first law, and how mass applies to inertia. Inertia applies to the first law because it is what makes the objects resist changes in their state of motion. Also, this part explained how an object remains in motion because of the presence of a force, not the absence of one. Finally, mass applies to inertia because objects have different tendencies depending on their individual masses.
 * Part C **
 * What exactly is state of motion? **
 * This part defines that a state of motion is controlled by its velocity and it also explains how inertia basically is the tendency to resist both velocity and accelerations.
 * Part D**
 * What is an unbalanced force?**
 * This part explains the different between a balanced and an unbalanced force. A balanced force as equilibrium so the object does not change its state of motion. An unbalanced force as unequal magnitudes so the object DOES change its state of motions.

**__Class Notes 11/15__** - Notes can also be found in last night's homework - Inertia is a property that measures how difficult it is to change an object's motion - *Weight is a force, pull of gravity on mass - w = (m)(g) - g = 9.8 m/s/s - N = w, then balances - *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 - If normal is greater than weight, then you are accelerating up - Term net force is generally used instead of unbalanced force

__**Homework 11/15/11 Newton's Laws Lesson 2 (a-d)**__
**Part A** **What is the meaning of force?** - A force is a push or pull on an object resulting from the object's interaction with another object - When this interaction ceases, the two objects no longer experience the force - Forces ONLY exist as a result of an interaction - There are two types of forces: contact forces and action-at-a-distance forces - Contact forces result when the two interacting objects are physically touching each other - Action-at-a-distance forces result when the two interacting objects are NOT physically touching each other - A force is a vector quantity **Part B** - The different types of forces are applied forces, gravitational forces, normal forces, frictional forces, air resistance forces, tension forces, and spring forces - Applied force is the force that is applied to an object by a person or another object - A gravitational force is the force with which the earth or moon attracts another object towards itself - Normal forces are the support forces exerted upon an object that is in contact with another stable object - Friction forces are the forces exerted on a surface as an object moves across it - Air resistance forces are special types of frictional forces - Tension forces are forces transmitted through a rope or chain - Spring forces are the forces exerted by a compressed or stretched spring upon any object that is attached to it **Part C** **What are 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 - These are special examples of vector diagrams **Part D** **What is a net force?** - The vector sum of all the forces that act upon an object - A net force is the sum of all the forces **How is a net force determined?** - Net forces can be determined the same way vectors were determined - Determined by summing the individual force vectors that are acting upon the object ** This part explained net force and how to determine it. A net force is the vector sum of al the forces that act on an object and it can be determined by adding up all the individual vectors (forces).
 * This part defines what a force actually is and gives examples of the two types of forces. I learned that forces depend upon the result of interactions and they only stop when the two objects no longer experience the interaction.
 * What are different types of forces? **
 * This part described all the specific different types of forces and gave examples for each. Although I knew of most of them, I learned more about all, especially spring forces and air resistant forces.
 * This part describes what a free body diagram is and how it can be drawn and utilized.

__** Home ** work 11/17/11 Newton's Laws Lesson 3 (a-b) __
**Part A** **What is Newton's second law?** - The second law pertains to the behavior of objects for which all existing forces are not balanced - Stats that the acceleration of an object is dependent of two variables- the net force acting upon the object and the mass of the object - Equation: fnet = ma **Part B** **What is the big misconception when it comes to Newton's Laws?** - People have trouble believing the implications of Newton's Laws - Some are unwilling to change their beliefs about certain situations and that is always an issue with Newton's laws. - The biggest misconception is that sustaining motion requires a continued force
 * This part describes that Newton's second law is and gives equations for how to solve problems involving it. It has a different meaning than Newton's first law so they are not the same thing.
 * This part shows how people often get confused with parts of Newton's Laws. Often, people cannot believe that an object does not require a force to sustain motion.