02.+Forces+in+1D+and+2D

Forces in ﻿1D and 2D  "To me there has never been a higher source of earthly honor or distinction than that connected with adva__n__ces in science." -Sir Isaac Newton

Forces In One Dimensions **Newton's First Law**

**The study of an object's motion is known as kinematics. The simplest case of kinematics involves motion in one dimension. Force ** **is a push and pull on an object. Newton's first law of motion is often stated as 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****. Forces in 1 Dimension you have to consider the vector.** ** ﻿Vectors have quantities such as postion, that have both magnitude and direction. The symbol //F// is a vector and represents the size and direction of a force, while Fonly represents only the magnitude. It is always important to identify the object of intrest. The object is called the system. **

**Free-Body Diagrams**

**When studying about Forces in 1D, it is always important to know how to make a free-body diagram. To make a physical model of the forces a cting on an object, apply the particle model and draw an arrow to represent each force. You also need to label each force including its agent. (As seen to the right.) The free-body diagram, to the right depicts two forces acting upon an object. Objects do __NOT__ necessarily always have four forces acting upon them. There will be cases in which the number of forces depicted by a free-body diagram will be one, two, or three. There is no hard and fast rule about the number of forces that must be drawn in a free-body diagram. The //ONLY RULE// for drawing free-body diagrams is to depict all the forces that exist for that object in the given situation.**

**Force and Accelaration**

**A net force causes an acceleration, which is a change in velocity. Whenever an object in motion changes direction,speeds up, or slows down it does so because a force is acting upon it. Force, acceleration, and velocity are all related. But, to determine how they are related you need to be able to exert a constant and controlled force on an object.** ** For example: A moving cart exerts a pulling force: the farther you move it, the greater the force with which it pulls back. If you always move the cart the same amount,you always exerts the same force. (Refer to picture on the right) **



** Inertia is the tendency of an object to resist change. For example,  The hitting of a golf ball is a good example of inertia. The mass of a golf ball is quite small and so its inertia is also small. However when the golf club strikes the ball the inertia of the ball is enough to prevent it moving instantaneously. It will take a fraction of a second for the ball to reach the speed of the club. During that time the golf ball will distort as shown to the right. ****Also in Newton's first law it explains equilibrium. Equilibrium is the condition in which the net force on an object is zero. Also note that being at rest is the case of constant velocity, V=0. You have to apply Newton's first and secod law which you try to figure out something about relative sizes of force.**

**REMEMBER:THE WORLD IS DOMINATED BY RESISTANCE NEWTON'S IDEAL, RESISTANCE FREE-WORLD IS NOT EASY TO VISUALIZE**.

**Newton's Second Law**
 * Newton's second law describes the connection between the cause of a change in an object's velocity and the resulting displacement. When thinking of Newton's second law, we know that force is proportional to mass and acceleration. In equation form it will look like this: F=MA **


 * Newton's Third Law **


 * Newton reconigzed that a single isolated force cannot exsist. Instead, forces always exsist in pairs. When two objects interact with one another it is called an action-reaction pair. The only thing to remember about action-reaction pair is that each force acts on a diffrent object. **** Newton's Third Law also applies to feild forces. **

Forces in Two Dimensions

** Forces in 2D you will use vectors and a little bit of math. One dimensional forces are horizantal and vertical. Forces in Two dimensional are at some angle of the horizantal and vertical dimensions. In common they both have some horizantal and vertizal component. Vector quantities are often represented by scaled vector diagrams. Vector diagrams depict a vector by use of an arrow drawn to scale in a specific direction. Vector diagrams were introduced and used in earlier units to depict the forces acting upon an object. Vectors can be directed due East, due West, due South, and due North. But some vectors are directed //northeast// and some vectors are even directed //northeast//, but more north than east. **

** The most common example of an object that is moving in //two dimensions// is a projectile. A projectile is an object upon which the only force acting is gravity. An object that is at rest is an projectile. An object that is thrown upward is an projectile. A projectile is any object that once projected or dropped continues in motion by its own inertia and is influenced only by the downward force of gravity. **
 * As is obvious from the animation above, the banana moves in a angle path in the presence of gravity. In the presence of gravity, the monkey also accelerates downward once he lets go of the limb. Both banana and monkey experience the same acceleration since gravity causes all objects to accelerate at the same rate regardless of their mass. Since both banana and monkey experience the same acceleration each will fall equal amounts below their //gravity-free path//. The banana misses the monkey, moving over his head. The banana passes as far above the monkey's head as it was originally aimed. So let's suppose that the zookeeper aims at the monkey, then the banana will hit the monkey. **

**In 2D forces friction is involved. Friction is surface resistance to relative motion, as of a body sliding or rolling. There are two types of friction, both opposes motion. These two frictions are known as Kinetic and Static friction. Kinetic friction is a type of friction that acts on moving objects and Static friction is a type of friction that exerted on one surface by another when there is no motion between the two surfaces.**

Essential Questions: These questions are randomly slected by the information on forces above. 1) What does Newton's Second Law state? 2) If there was an object in four forces, how many arrows would I draw on the free-body diagram? 3) What is the diffrence between Forces in 1D and Forces in 2D? 4) What does 2D forces involve that 1D forces don't? 5)What is the Diffrence from static and kinetic friction? 6)If a bowling ball had a mass of 100kg and an acceleration of 10m/s, what would be the force? 7) Which laws do you have to apply to figure out the size of force? 8) What is the only rule to remember about action-reaction pairs? 9) If a car had a mass of 2,600kg and an acceleration of 50mph, what would be the force? 10) In all of earth's equations, laws, and even dimensions: what is the most important rule to remember when facing forces in 1 and 2D?

__ Bibliography __ <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; font-size: 120%;">//Forces//,Colegio Franklin Delano Roosevelt,July, 1997:http://library.thinkquest.org/10796/ch5/ch5.htm?tql-iframe <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; font-size: 120%;">//PADRE//,1996-2011 The Physics Classroom:http://www.physicsclassroom.com/class/newtlaws/u2l2b.cfm