Unit 1-Motion

In this unit of physics I learned about motion. The first thing I learned about was Newtons first law of motion, the law of inertia. This law states that an object in motion will stay in motion unless acted upon by an outside force. It also stays that an object at rest will stay at rest unless acted upon by an outside force. We learned a lot about inertia through riding the hovercraft. We learned that inertia is directly related to mass and that the more mass something has the more inertia it has. Another thing we learned more about through the hovercraft lab was velocity. Velocity is the speed and direction of an object at any given time. The units for velocity is m/s. An object can only have a constant velocity if it has an unchanging speed and is going in only one direction. This means that if an object is rounding a corner, even if it maintains the same speed throughout the whole curve, it does not have constant velocity. The formulas we used for velocity were, for how fast, velocity(v) equals distance(d) over time(t). Or, v=d/t. The formula we used for how far was distance(d) equals velocity(v) times time(t). Or, d=vt. Another thing we learned about constant velocity is that when an object has constant velocity it means the net force is zero meaning it is in equilibrium. Net force is the force that is on an object. For example, if a person pushes a box with 200 newtons of force and the friction on the box is only 150 newtons, the net force of the box would be 50 newtons in the direction that the person is pushing. The last thing about motion that we learned about is called acceleration. Acceleration, though this sounds confusing, is how fast something is getting faster. For example, if a car is speeding up with a constant acceleration of 5 m/s^2 and it starts with a speed of 10m/s, then it will go an extra 5 meters for every second. The formula we learned for this was velocity(v) equals acceleration(a) times time(t). Or, v=at. This is the formula we used for acceleration when trying to determine how fast something was going at any of the given variables. The formula that we used for how far something had gone at any given variable was distance(d) equals one half acceleration(a) times time squared. Or, d=1/2at^2. 

What I have found difficult about what I have studied is really grasping the concept of inertia and understanding that something can be moving and will never ever stop unless some sort of force gets in its way or makes it stop. I also had a lot of trouble understanding the concept of acceleration and that it is a rate of how fast something is getting faster. The last concept I had trouble with was that of the different velocity and acceleration rates on an inclined plane.

The way I overcame these difficulties was actually through the labs we did in class. The lab with the marble helped me a lot with acceleration and incline confusion because I could physically see how the marks between each second got farther apart on an inclined plane as compared to them being exactly the same length apart on a flat plane. The way I understood inertia, the moment it clicked for me, was during the lab in the hovercraft when I saw that it would truly stay in the same place or travel until it hit the wall unless someone was there to stop it. 

My problem solving skills and effort towards class have been pretty good in my opinion. I don't really talk a lot in class but I think I ask questions when I don't understand something and I put it a lot of effort towards completing each assignment and understanding it once I complete it. I try really hard to do all the homework which I think helps a lot because it always helps me understand the concept that we are learning at that time. This is because it gives me a chance to really work it out for myself and I think that I have been putting a lot of effort towards homework so far. I am not really a "blogger" per say but I do try to include everything in each blog post and explain to my "readers" that I really know the material and that I could teach it to them. I think my use of creativity is lacking a little bit just because the only thing that I use to help me understand concepts is the labs. Though those help me to completely get a topic I think I could probably think outside the box and come up with my own ideas instead of using the ones from the textbook. I do, however, think my self-confidence in physics is pretty high because I know that even if I don't understand something right then I will eventually get it through all the different things we do to really dissect each topic.  I think communicating both by my spoken and written words could probably improve when it comes to spoke. As I said earlier I do not like to speak in class much at all but I think with the voice thread that is a really good way to get my voice heard because it is simply explaining that I know a topic and in class I normally don't have questions anyway.

My goals for the next unit is to be more creative when thinking about different ways concepts could apply to everyday life and to speak in class more. Also to not make the mistake I did on the trip problem again and really read over everything carefully until I fully understand what I am being asked.

The connections that I can make through situations in the world is, similar to the football question that we had on the test, a connection to soccer. The bigger people are put on defense while the smaller, slimmer, and faster people are put up top at forward. This is because the law of inertia shows us that the more mass a person has the more inertia. Therefore, a smaller person has a much easier time beginning to run toward the goal then a bigger person. Likewise, a bigger person is much harder to stop moving but also harder to start moving. This is why each person is put in a particular position. Another connection I can make to real life is to acceleration. Almost all kids love to get down on their backs and roll down a really steep hill. As kids, we view it as fun, but now that I've taken physics I am able to see why what happens happens. When you start rolling you move rather slowly, but you gradually get faster and faster until it feels like you are barely touching the hill at all. I now know that this is because you are accelerating and a constant rate. I also know that the only reason you slow down at the end of the hill is due to the friction between the ground and you.

This is a video I made with two other people in my class that, hopefully, should help clarify the concept of velocity. 

Intertia Picture

In this picture, my parents are putting up my christmas tree from this past christmas. As you can see, it accidentally tipped over, and my dad had to catch it as it was falling. If the only thing holding it up normally is the little red thing that our family puts it in, why doesn't it fall over more often? Well, according to Newtons first law of motion, the law of inertia, an object at rest will stay at rest unless an outside force acts upon it. Similarly, it states that an object in motion will stay in motion unless a force is acted upon it. This is why the christmas tree stays standing when all thats holding it up is that little red stand, and also why when my mom tipped it over it would have hit the ground if my dad had not been there to catch it.

Constant Velocity Vs. Constant Acceleration

The purpose of the lab that our class recently did with the marble is to physically be able to observe the difference in constant velocity and constant acceleration. Constant velocity means that something is rolling with not only constant speed but also in a constant direction. This means that, like the marble, the object is going the same amount of distance for each unit of time. For example, a car is driving in a straight line at 60 miles per hour (meaning it has constant velocity) constant velocity tells us that for every hour the car will go 60 miles, as long as it maintains its speed and direction. Constant acceleration, on the other hand, is when the car is getting faster at a constant rate. This is a little harder to understand than constant velocity, but it's a similar concept. If something, like the marble we used in the lab, is traveling with constant acceleration, it means that it will travel a farther distance than it did before for each unit of time. For example, if a car is speeding up with a constant acceleration of 5 miles per hour and it was originally going 40 miles per hour, it means that in the first hour it will travel 40 miles, the next it will travel 45, the next 50, and so on.
The way that me and my partner conducted this lab was, first, we drew a starting line for the marble. After the timer was turned on and we went through a few practice rounds, we rolled the ball at a constant speed and marked its place each time the timer sounded with chalk (so each second). After we managed to do this in a straight line, we measured the distance between each chalk mark and recorded what we found. We did this once on a flat table and once with the table raised on one side. Looking at each line, it was clear to see that the flat table displayed constant velocity and the table with the raised side displayed constant acceleration. This is because the flat table had an equal distance in between each chalk marking where as the raised table had more distance than the last between each chalk mark. After getting all of our information we put it into a chart on excel and graphed it. From there you could also clearly see the difference between velocity and acceleration because the graph of velocity was a straight line and the graph of the acceleration was a curve.
What I found out about how constant acceleration and constant velocity compare is that you can not have both at the same time. Because constant velocity implies constant speed, and constant acceleration implies speeding up at a certain rate, you can not have them both, ever. I also discovered that even though you can not have both, they are someone similar in that they are both a pattern. They are different in that constant velocity is one speed and therefore had a graph with a straight line and constant acceleration is changing speed therefore the graph is a curve.
The formulas used for constant acceleration are as follows; if you want to find how fast something with constant velocity goes you can use v (velocity) equals d (distance) divided by t (time). If you want to find out how far something with constant velocity goes you can simply rearrange that equation and get d (distance) equals v(velocity) times t(time). When it comes to acceleration, if you want to find out how fast something is going you use v(velocity, or speed) equals a (acceleration rate) times t (time). If you want to find out how far something with constant acceleration goes you can use the equation d (distance) equals one half a (acceleration) times t (time) squared. In that order, this is what the equations should look like:
-v=d/t
-d=vt
-v=at
-d=1/2at^2
The graphs that we found at the end of our lab by putting in all of our information showed a lot about constant velocity and acceleration. The graph of constant velocity was a straight upward line where as the graph of constant acceleration was an upward curve. The constant velocity graph was a straight line because nothing was changing. The only thing that was happening to the marble in this graph was that as more time went on more distance was gained. The constant acceleration graph, on the other hand, was a curve upward. This is because the speed was varying and as more time went on more distance was gained between each second.
The way we used the graph to help support the information that we found was we plugged the information in and got an equation out. This equation could be lined up with the equation v=d/t (the equation used to find how fast something goes with constant velocity). When we plugged both a distance and time in, both equations gave us almost identical answers. This meant that we had gotten near perfect data and that the marble was in fact rolling with constant acceleration or, in the other case, constant velocity.
A few important things that I learned from this lab that will help me for the future are, first of all, the different formulas. These will help a lot with finding the velocity and acceleration of objects in the future. Another thing I learned was that finding accurate data is a must because otherwise you can not actually understand what you are doing. The last important thing that I learned through this lab is that physics really can be applied to everyday life, even if you don't see it at first.

Trip Question

My initial thought on the answer to the trip problem was 60 mph, which as we discussed is what most people think the answer is at first. I thought that was the answer because the only thing I payed attention to in the problem was the average miles per hour instead of looking more into the per hour part. Because I only looked at the average, I added up the three speeds that would get the driver an average of 60 and figured "that was easy!" This was, obviously, not the correct answer. I learned that I need to read the problem carefully and figure out exactly what I am trying to find instead of basing everything off of my first impression.
The correct answer to the problem, which we found out later, is that the car needs to travel faster than the speed of light to go an average of 40 km/h in one hour. In order to solve this problem, you need to know the following. You need to know that the driver wants to travel 40 km/h in one hour. He has already driven 20 kilometers at an average of 40 km/h and then 10 kilometers for an average of 20 km/h. You also need to know that speed equals distance divided by time. If you rearrange that, you can get that time equals distance divided by speed. Therefore, for the 20 kilometers going 40 km/h equals .5, which is hours translates to half an hour. The 10 kilometers going 20km/h also translates to .5, which means the driver has already traveled an hour. Therefore, because he has already traveled an hour, he must immediately get to the end of the 40 kilometers, and the only way to do that is to travel at the speed of light.
What I learned about my problem solving skills is that I've been trained to skim over the problem and quickly solve it for what I think is the write answer. I will remember, after this experience, that I need to read the problem carefully and write things down in order to know how to get the correct answer.

Acceleration

http://www.youtube.com/watch?v=Vofs4znLgBQ

This is a video of a BMW speeding up as fast as it can showing its high acceleration rate. The car goes from stopped to a very high speed in just a few seconds. When the car is going straight it has a constant velocity. When the car is turning, however, it only has a constant acceleration because you can not have constant velocity without the object going in only one direction.