Changing Tides

How Tides Work!

Living on and island, I am constantly at the beach and in the ocean. After a long afternoon at the beach I notice how the ocean may have started at one point on the beach and then completely change after a few hours. In this resource, the nature of the tides and how the position of the moon and sun effect the tides are easily explained. There are two types of tides, Spring Tides and Neap Tides. Spring tides are when the tides are at their highest and lowest and there is either a full moon or a new moon and the sun is directly in front of the moon or the moon is directly behind the earth and the sun. Neap Tides are when there are half moons and the moon is on either side of the earth when the sun is not directly in front of it. These tides are due to the differences in forces on each side of the earth when is it revolving throughout the day. This is a great source that made it much easier for me to understand tides and the universal gravitational force.

Unit 2 Reflection

In this unit of physics, my class focused on Newton's second law, free fall, falling through the air, and projectiles.

Newton's second law states that acceleration is directly proportional to the force of an object, but inversely proportional to the mass of an object. We used these equations:

a=f

a=1/m

 For example, if a box was pushed with 2N of force compared to a box pushed with 5N of force, the box with 5N would accelerate more. If two boxes had  2N of force exerted on them, but one box weighed 10kg and the other weighed 5kg, the box weighing 5kg would accelerate mare than the box weighing 10kg.

In free fall, and object has only one force acting on it once it leaves its support force, this is the force of gravity. The force of gravity causes the object to accelerate at the constant rate of 9.8m/s^2, but in class we rounded it to 10m/s^2 unless we were working on a lab. Since the only force working on the falling object is gravity, the acceleration is equal to the forge of gravity (a=g). If you would like to find the velocity an object is falling at you use the equation v=gt In order to find the distance an object has fallen in free fall you use the equation d=(1/2)gt^2. You can rearrange these equations to find the time or solve for another variable depending on what information you have.  

When falling through the air, an object has the force of air resistance against it. When the force of air resistance is equal to the weight of the object falling (their net forces are equal) the object is at equilibrium or terminal velocity.  For example, what would fall to the ground first, a ping pong ball or a lead ball? Who would ave a greater terminal velocity?

If you dropped a ping pong ball and a lead ball at the same time from a tall building, the lead ball would fall to the ground first because it has a greater weight and needs more air resistance to reach terminal velocity. Since it needs more air resistance to reach terminal velocity, it has a greater terminal velocity than the ping pong ball. 

If you had dropped the balls from a moving air plane, then you would have to factor in the horizontal velocity. The balls would go the same distance vertically but would continue to move horizontally at the initial rate of the plane when they were dropped. So if the plane were going at a constant velocity then the balls would reach the ground directly under the airplane even though it was moving. 

Another aspect to falling through the air is the surface area. An example of this is a parachute, if someone falls through the air and reaches terminal velocity, in order to land safely the open up a parachute. The large surface area catches the air making the force of air greater than the parachuters downward force. In order for the parachuter to reach terminal velocity and have equal net forces again, the velocity of the parachuter must decrease. So a greater surface area, the lower the velocity.

Projectile motion was one of the more difficult things we learned in Unit 2. There are many different variables that effect projectiles including gravitational force, horizontal velocity, and vertical velocity. It is important to know that the horizontal velocity is constant throughout the projectiles motion like when it is free falling. Once a ball is projected through the air it reaches a peak of 0m/s vertically but would still be moving forward however fast it was horizontally. Then it begins to descend where its vertical velocity increases until it reaches the ground.

I could use the things I learned in this unit to determine how far I should go in order to throw a ball at a target or if I ever wanted to go skydiving, I would have a better understanding of when I was going at a constant speed and when I should start my parachute. I could have done better on my podcast, i wish i had been more detailed on Newtons Second Law. I think i dod very well on doing my homework and asked good questions in class. I really like the video homework we are given, it gets me an idea of what i should ask my teacher the next day in class. 

This is my Podcast on Newtons Second Law :

Batty about Physics

I took this photo at Yankee stadium this summer. Number 35, Justin Smoak of the Seattle Mariners, is preparing to hit a ball thrown by number 18, Hiroki Kuroda of the New York Yankees. In this photo the baseball is going at a constant horizontal velocity (neglecting air resistance) towards the batter, but the force due to gravity will pull the ball down so that the baseball accelerates in the vertical direction. The batter must know at what position the baseball will be at after the pitcher throws the ball so that he can hit it with the bat. The batter must know that the force of gravity will lower the ball otherwise he would aim the bat too high and would miss hitting the baseball completely.

Simply Falling through the Air

This source is easy to understand and gives a simple explanation of objects falling through the air. When an object falls through the air, the air resistance increases on the object so that the force of air is equal to the force of the object, putting the object at equilibrium or in terminal velocity.

Free Fall Fun!

In this video, the speaker clearly explains how free fall works compared to falling objects with the resistance of air. It also gives a great example of the experiment Boyle used to prove this theory. When an object is at free fall, gravity is the only force working on the object. This is so because as soon as an object leaves your hand or its support force and begins to fall, it no longer has that force acting on it.

Newtons 2nd Law

http://www.youtube.com/watch?v=fD1feqe1IyE&feature=related 

This video clearly explains and give easy examples as to what Newtons second law is. It is especially easy to understand because students made this video in order to help other students understand the law (one is named Margaret Anne too)! Newtons second law states that the acceleration of an object is directly proportional to the force exerted on it and indirectly proportional to the mass of the object. So as the force of an object increases so does the acceleration, but if the mass increases the acceleration will decrease.

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 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!}