Unit 3 blog reflection

Unit 3 was covered mostly by Newton's 3rd Law of Motion. Newton's third law of motion states that, "for every action there is an equal but opposite reaction." In the beginning of this lesson, we start to understand the concept of forces and interactions. We grasp a concept of forces such as pushing or pulling, but realize that no force or interaction occurs alone. Every force is part of an interaction between one thing and another. For example when a boxer uses his force to punch a large punching bag, the first force on the bag is from the boxer's fist, which causes the bag to dent. However, the punching bag also applies a force back on the boxer's fist. If the boxer was to punch a lighter tissue that was in midair, then the tissue could only exert how much force was exerted on it. This is why an interaction requires a pair of forces action on two separate objects.


After understanding this concept, we then moved to learn about Newton's Third Law of Motion and how it cooperated with action and reaction pairs. Newton's Third Law is summarized by stating, "whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first." But how do we grasp this concept using demonstrations. For example, when you walk, you interact with the floor. You push against the floor and the floor pushes against you. These pairs of forces are the same. So when stating "YOU PUSH on FLOOR" (This being the action) "FLOOR PUSHES on YOU" (This being the reaction) Next, this concept goes further in depth, which helps you understand how actions and reactions work when two object differentiate in mass. The book states, "As strange as it may seem, a falling object pulls upward on Earth  with as much force as Earth pulls downward on the object. The resulting acceleration of the falling object is evident, while the upward accelration of the Earth is too small to detect." When am apple is falling out of a tree the apple is pulling the Earth upward as much as the Earth is pulling the apple downward. Therefore "EARTH PUSHES APPLE DOWN" = "APPLE PUSHES EARTH UP." And to an extent we learn about how force is related to mass and acceleration proportionately with the demonstration of a cannon and a cannonball. When using the formula (F/m) = a, we know that if you have a smaller force then you are going to have a greater acceleration, and if you have a smaller acceleration you are going to have a greater force. We see this when demonstration a cannon firing. The force exerted against the recoiling cannon is just as great as the force that drives the cannonball inside the barrel. During the class we also played a game of tug of war that helped us understand the concept of forces applied. The guys competed against the girls in the game of tug of war, with one exception the guys were wearing socks on the hardwood floor. Anyways, the girls one because they were able to put more force on the ground which allowed them to pull harder.



As we moved into chapter 6, we started to learn alot about momentum. Momentum is simply inertia in motion. Or can also be defined as Momentum = (Mass x Velocity) We learned that a moving object can have a large momentum if either its mass or velocity are large or if both its mass and its velocity are large. One example we used in class was comparing a truck and a small car and seeing how their mass and speed compared to their momentum proportionately. Next, we learned about momentum. We learned that if the momentum of an object changes. then either the mass or the velocity or both changes. This is shown by the quantity force times time interval, or, Impulse = Ft. The greater the impulse exerted on something, the  greater will be the change in momentum. So therefor, Impulse = change in momentum. One example that really helped me grasp this concept was the example that showed that if a boxer "rolled with the punches then the impulse would be less."  This was shown as (little F)(BIG t)= (Big F)(little t) This is where the force over a greater time period would be less as opposed to the force being greater over a shorter time period. Then, we moved into the concept of objects bouncing. We learned that when an object hits something it has an initial impact and if it is not absorbed, has another impact that makes the object bounce off. This creates two forces on the object if the force is not absorbed. The demonstration where Mrs. Lawrence was in the rolling chair and threw and caught a heavy object and she continued to move backwards really helped me understand this more in depth. The final thing we looked at in this unit was the conservation of momentum.
From Newton's second law, we learned that to accelerate an object, a net force must be applied to it. This was generally the same in this chapter except written and explained differently. If we wished to change the momentum we would have to change the impulse. The demonstration the Mrs. Lawrence used where two cue balls were hit together and one stopped and the other kept moving helped me understand in real life terms of how momentum is transferred.


In conclusion, the things that really helped me be more of an in depth learned learner as opposed to more of a surface learner was trying harder on all my assignments. Throughout this unit I believe I only had a few missing homework assignments. I believe I completed most of my work on time and paid more attention to what I was working on. This has helped me grasp new concepts of physics and make me want to learn more. What also helped was the demonstrations Mrs. Lawrence did in class. Sometimes I believe that it is hard to have a grasp on concepts that are read out of a book. It is easier for me learn this way if they are demonstrated with real life problems. My goal for the next unit, and next semester is to try and keep up with this habit that I have developed over this unit and try to understand physics more in depth.

Unit 2 Reflection

In this unit, we learned many import concepts for physics. We learned all about Newton's Second Law and its behavior towards objects that may have an unbalanced force on them in the air. Newton's second law states that the acceleration of an object is dependent upon two variables - the net force acting upon the object and the mass of the object. The acceleration of an object depends directly upon the net force acting upon the object, and inversely upon the mass of the object. So as force acting on an increase, the acceleration of that object increases. As the mass of the object increases, the acceleration of that object decreases.



In other words acceleration is directly proportionate to force and inversely proportionate to mass. The equation below uses Fnet which can also be determined by mass times acceleration.

A = Fnet/m

We also learned about the concept of free fall with both inertia and acceleration. An object that is accelerating towards the earth without air resistance, (falling in a perfect vacuum) is in free fall. Free fall is any motion of a body where its weight is the only force acting upon it. When an object acceleration terminates, we say that the object has reached its terminal speed. Acceleration decreases because net force decreases/ Net force is equal to the weight minus air resistance, and air increases with the speed that an object is falling at.




This animation demonstrates that when an two objects are in free fall they hit the ground at the same time disregarding the mass difference of each object. It also demonstrates that when two objects are dropped and are encountered with air resistance they most likely will not hit the ground at the same time. This for many reasons. One reason being that each object may have a different surface area that causes more or less air resistance. Another reason is that they will have different mass and have a stronger force of gravity pulling them towards the Earth.

I think this blog reflection prepared me very well for the test. It helped me understand a few concepts that i still had questions about.

This video is proposes the question of "which object will hit the ground first." It seems simple that the heavy one will hit the ground first. However, without wind resistance the objects are in a perfect free fall. In this experiment, the objects don't have enough time to speed up to the acceleration due to gravity.

Newton's Second Law Resource

This video demonstrates how Newton's Second Law of Motion is proportional to force and the mass of an object. They take two of the same objects except one has a greater mass, and launch them out of a air cannon that distribute the same amount of force. Newton's states that the more massive an object is, the slower it will move. This is demonstrated in the video above.

Unit 1 Reflection

This unit was all about Newton's First Law of Motion. Newton's First Law is also defined as the law of inertia.

Every object continues in a state of rest or of uniform speed in a strait line unless acted on by a nonzero net force. 

Another way to say this is that an object at motion with stay in motion and an object at rest will stay at rest unless acted on by an outside force. The prime example of this law is where someone has set up a dinner ware set and pulls the table cloth out from underneath it. The dishes stay in their restful state because their inertia is greater than the force acted on it.



This same concept applies to objects in motion. An object at motion with continue to move without turning or gaining speed.  This was the concept demonstrated by our hovercraft lab. Although, this concept is mainly evident in space, we were able to recreate a friction-less environment by keeping the craft floating above the ground.



This video demonstrates that when she has to get stopped and started by on outside force. Before she is pushed she is at rest, after she is pushed she reaches constant velocity. This also can be defined as equilibrium.

Mass is also directly related to inertia. Mass is the coherent measure of how much matter somebody or something consists of. This is equally applied to inertia. The more mass a person has the more inertia they have. meaning it is harder to create that initial start and stop when being pushed on the craft.

Net force is where more than a single force acts on an object at one time. When two forces are acting on an object at once in opposite directions that are equal, the net force is 0N.

When one of those forces has an unequal amount of force then you simply subtract those two to find what the net force is. For example, if you and a friend pull on a box in opposite directions, and you are pulling at a force of 50N of force and your friend is pulling at 100N of force. The way to calculate that would be to take 100-50 to find that the net force equals 50N. However, there doesn't necessarily need to be an opposing force acting on the object to calculate its net force. If you push an object at force of 100 newtons and it moves then the net force on the object is 100N. This is because the force acting on the object is greater than the friction acting as the resisistance.


As we move into Chapter 3 we are introduced to the properties of linear motion. Speed is the distance covered per unit of time, or Speed = distance/time.
This same concept is applied when trying to calculate the average speed of an object. The formula for that is Average speed = total distance covered/time interval

The difference between velocity and speed is that velocity shows the direction an object is moving in. If a car is moving around a track at 6m/s it is traveling at a constant speed but it is changing direction so the velocity changes. This proves that  it is possible to have a constant speed but changing velocity, but not possible to have constant velocity but changing speed.

It is possible to change the velocity of something because of its changing speed, and direction or both speed and direction. We can calculate acceleration by how quickly an object's velocity changes.

Acceleration = change of velocity/ time interval

For example, we can relate this to how the change in someones velocity is defined as acceleration. If someone is accelerating then they are rapidly gaining speed or slowing down, but they are not traveling at a constant velocity.

Acceleration can be constant or increasing depending on the force that is acted on it. The book demonstrates 3 ramps that a ball is rolling down. All have increasing acceleration to a point, but some remain constant and others keep increasing.
The way to calculate increasing acceleration is multiply the acceleration over a time interval.

Constant V Vs. Constant A Lab

1. I believe the purpose of this lab was to demonstrate the difference between constant velocity and constant acceleration in a real life situation. This lab interactively showed how constant velocity and constant acceleration  varied by the markings on the table.

2. The difference between constant velocity and constant speed is that constant velocity is where the speed does not change nor does the direction it is traveling. Constant speed is where the speed of an object is increasing evenly because of the acceleration increasing.

3. During this lab, there was a metronome that made a beat for every half second. My group and I propped a table so it was on a slope. We rolled the ball down the slope marking every half second where the ball rolled.

4. This proved that the ball was rolling at constant velocity. Each mark was measured and was evenly spaced out. With constant acceleration the distances between the marks gradually increased.

5. The formulas used in this lab were: to find velocity V= d/t
To find how far the object went we used d=1/2 at^2
And the equation of the line is y=mx+b

6. The line for constant velocity was a straight diagonal line that gradually increase with the same amount of time and distance. The constant accelerating graph increased speed over a shorter amount of time

7. When you entered a time into the x variable you get the distance at the rate of acceleration that was given.

8. In this lab I learned that its easier to graph your data and calculate the line it forms. I also learned that you must repeat an experiment multiple times to record results that support the problem of the lab.

British Guy Explains Acceleration

So pretty much what this guy with the super British accent is saying is that acceleration can be classified as positive, negative, or zero acceleration, depending on the change in velocity. When the speed of the bus increases with time, then the acceleration is positive. It is negative when the speed decreases. Every object is set with zero acceleration whether it is at rest or constant velocity.

Post Hovercraft Lab

a. I'm not entirely sure what riding on the hover craft because I never got a chance to participate. But, I believe those who did ride it felt as though they we gliding and would never stop. The hover craft is different from riding on any other vehicle because of the lack of surface friction, you feel like you would go on forever.

b. I learned that inertia has a lot to do with the mass of something. The greater the mass the more the harder the initial force for the object to start is harder to create, and the same with slowing down. I also learned that while gliding on the hovercraft, equilibrium is reached when the craft reaches constant velocity.

c. Acceleration depends on the initial push of the object for it to start moving. The harder the initial opposite force acting on it the higher acceleration the craft is going to have.

d. Based on this lab, I would expect to have constant velocity when the craft fished accelerating and reached the speed it would remain at.

e. Some members during this lab were harder to stop because some had more mass than others. As I explained earlier mass and inertia coincide with one another. With more mass, that means the object is harder to accelerate both negatively and positively.

Inertia Demonstration

The ball is constantly spinning because of the acting force of the curved edges in the glass bowl, after being acted on by the outside spinning force.

Introduction

What do you expect to learn in physics this year?

This year in physics, I expect to learn many different concepts that deal with understanding what physics is all about. The first thing I expect to learn is the concept dealing with the forces of nature. I believe this will help me get a better grasp of all of regions of sciences. The next thing I intend to learn are Newton's laws. And lastly, I would like to learn something about the basics of mechanics.

Why do you think studying physics is important? 

Studying physics is very important because it is the foundation of all the other sciences. Physics is the study of the laws of nature that apply to people’s everyday lives.  Physics helps people get an understanding of how everything living and nonliving around them works.

What questions do you have about physics this year?

The questions I have about physics this year are, will we be learning about any mechanics or basic machines? Are we going to lean anything about how certain every day items work? What can physics be used for outside the classroom? I would like to learn about how physics is used in everyday things, whether its dealing with mechanics or construction.

What goals do you have for yourself in physics this year?

 Some of my goals for physics this year include, getting a better background for understanding different sciences, understand how physics is used in our every day lives, and try to actually understand this class in depth and not just be a surface learner.