Unit Summary 1

Things I learned:
       One of the first topics that we addressed in this class was that of inertia and Newton's fist law.
Sir Isaac Newton's first law is that of inertia, and it states that: An object in motion will stay in motion, and an object at rest will stay at rest, unless acted upon by an outside force. This is Newton's first law and it explains the concept of inertia.
 
    This is a video that my group made explaining this concept of inertia.  We use multiple examples to show how inertia will keep an object moving unless that object is acted upon by an outside force, and how inertia will keep an object at rest unless it too is acted upon by an outside force.
Pay particular attention to the example with the cup of water, and the piece of paper being pulled out from underneath it.  Because in that example we are shown a property of inertia, and that property is that:
Inertia and mass are directly related, as mass increases, so does the inertia of an object.  And as mass decreases, the inertia of the object decreases.
                                                                                         mass ^=inertia^

   

       

  Another topic that we have spent time learning about this unit is Net Force and Equilibrium.
Net force is the overall sum of the force acting on an object.  lets see an example:

Say we have a box, and this box is being pushed with a force of 50 N to the right. (Hold on, before we go any further, let me explain to you what a "N" is and the other ways in which we measure force and mass. Mass is always measured in kilograms=kg.  While force is measured in Newtons=N.  It is important to understand the difference between the to units because you can not say that an object was being pushed with 10 kilograms of force, you could however say that the object was being pushed with 10 Newtons of force.)   Ok so back to net force and the example.
  The box is being pushed with a force of 50 N to the right.

                                                       50 N -----> [___]
But then something else begins to push on the box in the opposite direction to the left with 100 N of force.

                                                      50 N -----> [___]<-----100 N
At this point what is the Net Force on the the box?   lets do some simple math to find out.
Subtract 50 N from 100 N to find the answer is 50 N of net force. And the 50 N of net force are going to the left .                                                                       Net Force= 50 N



Now lets introduce the concept of equilibrium.  Lets take the same box, but this time it is just sitting still on a table.  And this time we know the box weighs 10 kg.
                                                                                10 kg
                                                       _________ [___] _______
                                                                    10 kg
Because the box weighs 10 kg, the table is pushing back against the box with 10 kg as well.  So using what we know about net fore, we can conclude that the net force acting on this box is 0 N.  When there is no net force acting on an object this is called Equilibrium.  Equilibrium is obtained whenever an object is experiencing zero net force, and can happen either while moving or at rest.
 
I got to experience what it is like to be at equilibrium while moving when we rode the hovercraft. the hover craft was drifting along with 0 net force and rode on a layer of air.  


       
                      Speed and velocity are two similar topics but vary from each other in very specific and important ways.   To find the speed of something we must know how much distance it is covering in some amount of time. to do this we use the equation: speed equals distance over time.
                                                                          speed = distance / time  
                                                                                      or                                      v=d/t
                                                                          velocity = distance / time

When we are measuring the speed or velocity of an object the most common measurement is                  meters per second.  =   m/s
                       
                                                                      SPEED VS. VELOCITY
     This is where speed and velocity begin to differ.  Velocity requires a specific direction to be maintained if you want to keep the velocity.  this direction is show using arrows called vectors.
                                                                  vector = ----->
Speed on the other hand does not allow for vectors.  This is because speed can remain constant while changing direction.  
              There are three ways to change the velocity of something.
                 1: by increasing speed
                 2: by decreasing speed
                 3: by changing direction
An important concept to understand is that you can have a constant (meaning unchanging) speed, without having a constant velocity.  But you can not have ha constant velocity without having a constant speed.

An example of this is a race track.   Lets say that he car is traveling at a constant speed of 200 m/s around the track. its speed is constant, but every time it makes a turn and changes direction, it also changes its velocity.



              Acceleration is a change in velocity over time.  This equation is written as
                                                                   
                                                                    acceleration = change in velocity over time
                                                                                   or
                                                                    a = change in v / t
 What acceleration really is, is the rate at which the speed of an object is increasing.  When we measure acceleration, we use  meters per second squared =  m/s^2.  
 One specific example of acceleration that is the same in all theoretical situations is the acceleration of an object due to the force of gravity.  Acceleration due to the force of gravity is 9.8 m/s^2.   What this means is that when an object is being pulled down to earth by gravity, the object is traveling at a constant increasing speed of 9.8 meters every second.    

            I have used the word constant to help talk about both velocity and speed. Now lets see what equations explaining these concepts actually look like and how we can use them to find out how far or how fast something is traveling while at constant velocity or acceleration.

                                constant velocity:                             vs.                      constant acceleration:
       How far? distance = velocity multiplied by time           How far? distance =  one half of acceleration
                                        or                                             multiplied by time squared.
                                      d=vt                                                                    d=1/2at^2
How fast? velocity = distance over time
                        v=d/t                                                        How fast? velocity = acceleration x time            
                                                                                                                v=at

This is the video Claire, Jillian, and I made to demonstrate Newtons first law of inertia.

Riding on a hovercraft feels like you are asleep in bed, but you can feel your body start to drift off. it is a smooth gliding feeling unlike any other.  I would tell you to be willing to let go of control and to just enjoy the feeling of no resistance (equilibrium).  It is different from any other form of transportation in that you do not feel the surface you are moving over.  I learned that when you are pushed on the hovercraft that once you are moving you have reached an equilibrium or constant velocity, and that the net force being implied on you are 0 Newtons.  Acceleration depends on the force applied in a direction, versus the force applied in the opposite direction. Constant velocity would be obtained when the hovercraft is no longer being pushed and is moving on its own.  Some members were harder to stop than others because they had greater mass, and therefore greater inertia.

Questions and No Answers (Physics Day 1)

     This year (2014), I, David Schill expect to learn everything! No really I do, because from what I have heard, physics is everything.  That means that I expect to learn why I cant hold a rope under my feet, pull up hard and quick, repeat this step over and over, and do some form of levitation. Secondly, I expect to learn why objects in free fall can only go as fast as their terminal velocity will allow them.  Thirdly, I expect to learn why certain metals conduct electricity better, or worse than other metals.
I think that studying physics is important because physics is what makes all the sports I love possible.  Physics explains why when your hands are you are cold you can rub them together and create heat.  And it is important to study physics so that automobile engineers  can better protect us from the forces involved in a crash.  This year my goals in physics include to maintain at least a B average, to test better than I have in previous science courses, and to come away with an applicable understanding of physics.   

Inertia

I Chose to use this video as an example of Newton's first law, because I feel it is a very relevant and serious real world example of inertia. The part of this video that really reviled new information and challenged the way that I saw and understood the role inertia in a car accident, begins at 50 seconds and explains what the purpose of head rest are.  The typical though on what causes whiplash in a car crash is that the neck violently snaps backwards.  While what is really happening is a gruesome example of Newton's first law which states that an object at rest will stay at rest, and an object in motion will stay in motion, unless acted upon by an outside force.   And what this video reviles to us is that the whiplash is not caused by the head moving away from the body, but instead is caused by the body moving away from the head.