Ch4_hwangti

= Chapter 4 = toc

Newton's Laws - Lesson 1:Newton's First Law of Motion
Newton's First Law of Motion, also known as the law of inertia, states that 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. Basically, the Newton's First Law is saying that an object will keep doing what it is doing. A real world application of Newton's First Law of Motion is when a person is driving with a cup of coffee. If the makes a sudden stop, then the coffee will spill since the coffee is still moving.
 * A)**What is Newton's First Law of Motion and what are some real world applications for it?

Inertia is the resistance an object has to a change in its state of motion. Because mass is solely dependent to inertia, the greater the inertia is, the greater the mass will be. Galileo discovered during an experiment that when he rolled a ball down an incline, the ball would reach nearly the same height it began on on the other inclined plane. He then reasoned that if he rolled a ball down an incline, the ball would continue to roll on a flat plane if there was no friction present. Force does not keep an object moving. It actually is the opposite. Force is actually needed to stop an object from moving. Friction keeps an ball from rolling nonstop.
 * B)**What is inertia and what does it have to do with mass? How did Galileo contribute to understanding inertia? What does a force do if it does not make an object keep moving?

The state of motion of an object is defined by its velocity. Because of this, inertia could be redefined as a tendency of an object to resist acceleration.
 * C)**What is "state of motion" and how is velocity and inertia related to it?

A balanced force is when 2 opposing forces and equal but are facing opposite directions. There is equilibrium. An unbalanced force is when 1 opposing force is greater than the other so there is no equilibrium.
 * D)**What is the difference between a balanced and unbalanced force?

Newton's Laws - Lesson 2:Force and Its Representation
A force is a push or pull upon an object resulting from the object's interaction with another object. The two categories that different forces are put into are contact forces and action-at-a-distance forces. Contact forces are those types of forces that result when the two interacting objects are perceived to be physically contacting each other. Some contact forces are friction, tension, and normal force. Action-at-a-distance forces are those 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 physical separation. Some action-at-a-distance forces are gravitational force and electrical force. Force is a quantity that is measured using the standard metric unit known as the Newton. A Newton is equal to 1 kg*m/s 2.
 * A)**What is force and what kind of forces are there?

Gravity Force or Weight - force that pulls the object downwards towards the center of the earth (w=m*g) Normal Force - support force exerted on an object that is in contact with another stable object Friction Force - exerted by a surface as an object moves across it (there are 2 types of friction: sliding and static friction) Tension Force - transmitted through a rope when it's pulled tight by forces acting form opposite ends
 * B)**What are the different types of forces and what is the difference between mass and weight?

Weight - the force of gravity acting upon an object Mass - the amount of matter that is contained by the object

To draw a free body diagram, one must first separate the system from the environment. Then draw arrows with the appropriate length to show the magnitude. Then label each arrow with the respective force that is acting with that arrow. If there are 2 arrows of the same force, then write subscripts to indicate which is which such as T 1 and T 2.
 * C)**How does one draw a free body diagram?

A net force is only present if the forces are unbalanced. The net force is the vector sum of all forces acting upon the object.
 * D)**How do you determine what the net force is?

Newton's Laws - Lesson 3:Newton's Second Law of Motion
**A)**What is Newton's Second Law of Motion?

Newton's Second Law of Motions deals with the behavior of objects when all of the existing forces are not balanced. It states that the acceleration of an object is dependent upon two variables - the net force acting upon the object and the mass of the object. The acceleration of an object depends directly upon the net force acting upon the object, and inversely upon the mass of the object. In addition, acceleration points in the same direction as net force. The equation for Newton's Second Law is: a = Fnet / m.

The big misconception about Newton's Laws is that objects in motion need needs to constantly have force applied to it in order for it to keep moving.
 * B)**What is the big misconception?


 * C)**What is static equilibrium?


 * D)**How does a person find out what net force is equal to if it is not given?


 * E)**How does a person solve a problem when there is some sort of incline?


 * F)**How does a person solve a problem when there is more than one system?