http://www.youtube.com/watch?v=fD1feqe1IyE&feature=related
Sunday, September 30, 2012
Newtons 2nd Law
Tuesday, September 25, 2012
First Unit Reflection
I have learned a lot in Physics so far, the first thing I learned about was inertia. I learned that inertia is the push or pull of an object. Inertia is a concept, not a law or thing that makes things move. I also learned about Newton's first law which is an object in motion will stay in motion or an object at rest will stay at rest unless acted upon by an outside force. My class tested this by using a homemade hovercraft in our gymnasium. When the hovercraft was at rest it did not move, but when the hovercraft was set into motion it wouldn't stop unless someone used a force to stop it. In this setting there was no friction because the hovercraft was hovering above the ground so there was no friction force acting on the hovercraft while it was at rest or moving. Another thing I learned while doing this experiment was that the more mass something has, the harder it it to move it and mass is the measure of inertia an object has. So, the more mass an object has the harder it is to put it into motion or stop.This experiment gave a great understanding of inertia and Newton's first law.
I applied Newtons first law into real life from when you are rear ended in a car. Both you and the car are originally at rest, when all of a sudden another car hits your car from behind and forces it into motion. Based on Newton's first law your head is at rest and wants to stay at rest. so when the car moves your head stays at rest and hits the headrest of your car. If the headrest were not there, then your head would be tilted all the way back and could cause serious neck damage. Newton's first was used to save your life in a car accident, how cool is that?!
Another thing we learned about was net force. When an object is at rest or is moving at a constant speed the net force is zero. This is because there are equal and opposite forces working on the object, which also means the object is at equilibrium. The net force of an object is measured in newtons, so the force being exerted on an object could be 50 newtons or 10 newtons. In order to find the number of newtons of force and object has, you subtract the number of newtons exerted on one side of an object from the number of newtons of force from other side of the object. For example, if a force of 50 newtons were being exerted to the left of an object but 100 newtons were being exerted to the right of an object then the total net force would be 50 newtons to the right of that object.
Some other things we learned about were speed, acceleration, and velocity. Velocity is the distance traveled over time and is dependent on the direction, acceleration is the change in velocity over time, and speed is also the distance over time. The equation for velocity is v=d/t, for example if a car goes 20 meters in 10 seconds the the equation would be v=20/10 and the velocity of the car would be 2m/s. Lets say the car was originally at rest, if you wanted to find the acceleration of the car you would use the equation a= Δ v/t. So a=(2m/s-0m/s)/10 seconds which is equal to 0.2m/s^2 which would be the acceleration. What is you didn't know the velocity or the distance? Then you would use the equation d=1/2at^2. First you would plug in the 0.2m/s^2 for a and 10 seconds for t. When you plug in those numbers, you should end up with the distance 20 meters. All of these equations can be connected in some way!
So what is the difference between a constant velocity and a constant acceleration? In constant velocity, the speed of and object never changes and neither does the direction of that object. In constant acceleration, the object is constantly gaining speed at a certain rate. Something most people do't know is that you can move forward while accelerating backwards. for example when a car is stopping at a stop light the car is acceleration backwards in order to stop but still moving forwards! How cool is that?!
I learned a lot of really interesting things in this unit that i can use and relate to in everyday life!
I applied Newtons first law into real life from when you are rear ended in a car. Both you and the car are originally at rest, when all of a sudden another car hits your car from behind and forces it into motion. Based on Newton's first law your head is at rest and wants to stay at rest. so when the car moves your head stays at rest and hits the headrest of your car. If the headrest were not there, then your head would be tilted all the way back and could cause serious neck damage. Newton's first was used to save your life in a car accident, how cool is that?!
Another thing we learned about was net force. When an object is at rest or is moving at a constant speed the net force is zero. This is because there are equal and opposite forces working on the object, which also means the object is at equilibrium. The net force of an object is measured in newtons, so the force being exerted on an object could be 50 newtons or 10 newtons. In order to find the number of newtons of force and object has, you subtract the number of newtons exerted on one side of an object from the number of newtons of force from other side of the object. For example, if a force of 50 newtons were being exerted to the left of an object but 100 newtons were being exerted to the right of an object then the total net force would be 50 newtons to the right of that object.
Some other things we learned about were speed, acceleration, and velocity. Velocity is the distance traveled over time and is dependent on the direction, acceleration is the change in velocity over time, and speed is also the distance over time. The equation for velocity is v=d/t, for example if a car goes 20 meters in 10 seconds the the equation would be v=20/10 and the velocity of the car would be 2m/s. Lets say the car was originally at rest, if you wanted to find the acceleration of the car you would use the equation a= Δ v/t. So a=(2m/s-0m/s)/10 seconds which is equal to 0.2m/s^2 which would be the acceleration. What is you didn't know the velocity or the distance? Then you would use the equation d=1/2at^2. First you would plug in the 0.2m/s^2 for a and 10 seconds for t. When you plug in those numbers, you should end up with the distance 20 meters. All of these equations can be connected in some way!
So what is the difference between a constant velocity and a constant acceleration? In constant velocity, the speed of and object never changes and neither does the direction of that object. In constant acceleration, the object is constantly gaining speed at a certain rate. Something most people do't know is that you can move forward while accelerating backwards. for example when a car is stopping at a stop light the car is acceleration backwards in order to stop but still moving forwards! How cool is that?!
I learned a lot of really interesting things in this unit that i can use and relate to in everyday life!
I think i found it most difficult to understand how acceleration slows down on a curved slope and how acceleration can go backwards. I finally began to understand the curved slope when we answered the question on a worksheet and it was drawn out on the board. The slope at the top of the curve is more drastic than the slope of the bottom of the curve, so the acceleration is greater at the top of the curve than the bottom. Thus, the acceleration decreases as it goes down the curved slope. As for the acceleration backwards, i finally understood that when I applied it in my podcast. I was reading my notes on it into the computer and then i finally understood it when i said it out loud. When a car is moving and wants to stop, it will still be moving forward but losing speed at a certain rate, so the acceleration is decreasing or moving backwards.
I believe that I put a lot of effort into this class. I always did my homework and tried very hard on assignments. The few labs we did I completed and understood relatively well. Also, my blogs were all complete and well written. I did forget to comment on one blog though, that was one thing I did wrong. Anna was my partner for the podcast and I think we did an awesome some job on it. We were very organized and wanted it to look really good. We didn't finish it in class on Saturday, but we took our lunch time to post it to youtube. I think that if I continue with my current work ethic in this class I should do well. The math parts of physics I understand really well and the factual parts I begin to understand after we go in depth on them, which we always do in class. I loved working with Anna, I think that group project are fun since you get to learn how they see physics. I definitely want to work with more people in my class this year.
My goal for the next unit is to understand more about Newton's laws and different concepts or laws found in physics because I was so amazed by how many ways Newton's first law applied to real life. I can't imagine all the other laws that will apply in real life too! I will do this by paying attention in class and trying to see these things being done in real life outside of class rather than constraining physics to the classroom. Physics has been a very good class for me, it really is fun!
This is the podcast about acceleration that I did, I hope that you enjoy it!
Sunday, September 16, 2012
Acceleration, Velocity, Physics Oh My!
The purpose of this lab was to differentiate acceleration from velocity. A constant acceleration is the rate in which an object speeds up or slows down within a certain amount of time (m/s^2, miles/h^2, etc.) Constant Velocity is when an object is going at a constant speed and direction, so the object could not turn or have an increasing or decreasing speed.
In this lab I found the difference between acceleration and velocity by rolling a marble across a table. First I rolled the marble down the flat table and marked every half second, then i used microsoft excel to graph the distance and time of each mark. The graph was a straight line with points that were equidistant from each other. Then I put the table at an incline and rolled the marble down it. When I marked the table this time, the marks got farther and farther away from each other. Then when i graphed the data the points were at a curve and separated from each other over time.
In this lab I found out that constant velocity and constant acceleration are very different from each other. Velocity is dependent on time and direction where as acceleration is dependent on time and velocity.
When finding the constant velocity and constant acceleration I used two formulas. For constant acceleration I used a=v/t ( acceleration=velocity/time) and for constant velocity I used v=d/t(velocity=distance/time).
When graphing the data I was able to find the equation for each graph by using the equation of a line (mx+b=y) where y=distance, x=time, m=slope, and b=0 because that was the beginning distance and time of the marble. This equation could be used to find potential points on the graph of where or when the marble will reach a certain point on the table.
The three most important things I learned in this experiment was the difference between acceleration and velocity, how to use excel to graph data, and how to use equations to determine potential points or times of moving objects.
In this lab I found the difference between acceleration and velocity by rolling a marble across a table. First I rolled the marble down the flat table and marked every half second, then i used microsoft excel to graph the distance and time of each mark. The graph was a straight line with points that were equidistant from each other. Then I put the table at an incline and rolled the marble down it. When I marked the table this time, the marks got farther and farther away from each other. Then when i graphed the data the points were at a curve and separated from each other over time.
In this lab I found out that constant velocity and constant acceleration are very different from each other. Velocity is dependent on time and direction where as acceleration is dependent on time and velocity.
When finding the constant velocity and constant acceleration I used two formulas. For constant acceleration I used a=v/t ( acceleration=velocity/time) and for constant velocity I used v=d/t(velocity=distance/time).
When graphing the data I was able to find the equation for each graph by using the equation of a line (mx+b=y) where y=distance, x=time, m=slope, and b=0 because that was the beginning distance and time of the marble. This equation could be used to find potential points on the graph of where or when the marble will reach a certain point on the table.
The three most important things I learned in this experiment was the difference between acceleration and velocity, how to use excel to graph data, and how to use equations to determine potential points or times of moving objects.
Wednesday, September 12, 2012
Tricky Trip Problem
In class the other day, I was assigned a worksheet with a tricky problem. It asked me to find the average speed a car would have to go, after it had already traveled certain speeds, in order to have a total average of 40 km/h. When I was first trying to solve the problem I though that I needed to average the speeds. I got the answer 60 km/h, but i thought that it didn't seem like enough time. Then I tried to use the average speed equation as=d/t, but that wouldn't help me at all. I was extremely confused until a classmate explained how to solve the problem to me.
When I was trying to solve the problem, I wasn't paying attention to the time the car had to travel, which was only one hour. By the time the car had traveled thirty kilometers, it had already been an hour long. In order for the car to have an average of 40 km/h, the car would have to travel at the speed of light and instantaneously reach its distance goal of 40 km.
I learned to carefully read problems so that I would understand them completely. This tricky problem has helped me to realize that even the smallest details of a problem may be the most important part and that the answer may be in the question itself.
When I was trying to solve the problem, I wasn't paying attention to the time the car had to travel, which was only one hour. By the time the car had traveled thirty kilometers, it had already been an hour long. In order for the car to have an average of 40 km/h, the car would have to travel at the speed of light and instantaneously reach its distance goal of 40 km.
I learned to carefully read problems so that I would understand them completely. This tricky problem has helped me to realize that even the smallest details of a problem may be the most important part and that the answer may be in the question itself.
Saturday, September 8, 2012
Velocity and Acceleration
This video clearly explains Velocity and Acceleration. It uses many examples such as a toy car, and a real car in order to explain both concepts. Velocity is distance over time or v=d/t, while acceleration is change in velocity over change in time or a=delta v/ delta t. By measuring the distance and time, she was able to determine the velocity and acceleration of the toy car. Afterwards, she gives you a real life example, using a real car. This is a great source to use in order to understand velocity and acceleration!
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