DO WORK

Welcome to Unit 6, our last unit of the semester! We have done so much work in this semester that it seems right to end off the year with learning about

Work, Energy, and Power!

Work is defined as any change in energy (or the little triangle and a big E). To find variables while working with work, we use:

Work = Force x Distance

or W = F(d)

The units of work are Newton meters (Nm), otherwise known as Joules (J).

We also learned about the Law of Conservation of Energy which states that in an isolated system energy cannot be created nor destroyed, it just changes forms. Therefore, change(in) = change(out).

There are two kinds of energies:

Gravitational Potential Energy (PEg) - Energy of Position

Gravitational potential energy = mass x gravity x height

PEg = mgh

and...

Kinetic Energy (KE) - Energy of Motion

Kinetic energy = 1/2 x mass x velocity squared

KE = 1/2mv^2

The next thing we talked about was POWER. Power is the rate at which work is being done.

Power = change in energy/time

Power = work/time

The units of power are Joules/seconds, otherwise known as Watts.

When analyzing a force x distance graph, you should always remember: The area under the curve of a force x distance graph is WORK.

The last aspect of this unit that we covered so far was springs and elastic potential. The equation when dealing with springs is:

PEs = 1/2kd^2

where PEs is the elastic potential, k is the spring constant, and d is the distance stretched.

The bigger the spring constant, the harder it is to pull or stretch the spring. Therefore, with a larger spring constant, you need to apply more force.

When I was studying at Coffee Bean and Tea Leaf this afternoon, I accidentally dropped my pencil. I noticed that this was exactly like one of the problems that we discussed in class!

Let's say that my pencil with a mass of .4 kg fell to the floor from a table that was 2 m high. Can we find it's velocity?

Of course we can!

We first use the gravitational potential energy equation to find the amount of energy.

PEg = mgh

PEg = (0.2 kg)(10 m/s^2)(2 m)

PEg = 4 J

Then we use the kinetic energy equation to find the velocity.

KE = 1/2mv^2

4 J = 1/2 (0.5 kg)(v^2)

2 = (0.5 kg)(v^2)

1 = v^2

v = 1 m/s

Yay! We just did work!

Beyond Thankful!

It's the most wonderful time of the year! The holidays give us a chance to appreciate all that we have and give thanks to those that deserve it. So for one, thank you Mr. Coach Chris for giving us this wonderful assignment to do a blog post over the break! This four-day break gave me an opportunity to reflect on what I am thankful for relating to physics! It wasn't really that hard to think of what I am thankful for relating to physics because physics is all around us!! I am thankful for physics because it plays such a large role in our everyday lives that without it, we would probably have a hard time living.

What am I thankful for in physics?

Acceleration

Acceleration (the rate at which the velocity of a body changes with time) plays a huge role in my life and without it, it be stuck! Literally! If my car couldn't accelerate, I'd be stuck at home (too lazy to walk), not able to get to the Thanksgiving party where there is the loads of food! I also wouldn't have been able to get to Ala Moana to do damage on Black Friday!

Relative Motion

I am also very thankful for relative motion because without it, I wouldn't be able to talk to my friends while walking in the halls or say hi to my friend in a car that is going at the same velocity as my car. If I am walking at 2 m/s and my friend is walking at 2 m/s too, relative to each other, we are moving at 0 m/s, allowing us to hold a conversation!

Friction

Friction is so important! It helps us walk, run, stop, and our overall movement because it is the opposing force that acts when objects move against other objects. 

Gravity

I am so thankful for gravity!! Without gravity (9.8 m/s^2), I wouldn't be able to sit down with my family and eat food that didn't float around.

Here is a plate of my amazing food (round 1)!! I wouldn't have been able to enjoy my Thanksgiving break without physics!

There is so much to be thankful for, not only during the holidays, but every day! 

Momentum!!

Our new unit that we are concentrating on focuses on...

Momentum!

Momentum is abbreviated with the letter P (I know, m was already taken). Momentum is the quantity of motion of a moving body, measured as a product of its mass and velocity.The law of conservation of matter states that in a isolated system, momentum will be conserved. Impulse is the change in momentum. We also learned a couple of equations...

Momentum(in) = Momentum(out)

Momentum = mass(kg) x velocity(m/s)

(Therefore, momentum's units are kg(m/s))

Impulse = P(final) - P(initial)

(Therefore, impulse is the change in momentum)

Impulse = F (average force) x t (time)

One of the most important concepts that we learned about had to deal with the last equation: Impulse = (avg force)(time). This equation explains the relationship between impulse, force, and time. When impulse increases, force and time also increase (direct relationship). Force and time have an indirect relationship that means that as force increases, time decreases and vice versa.

My clumsy sister always drops her phone! She drops it outside, inside, off the table and anywhere imaginable. Today, she dropped her phone twice: once on the carpet in my living room, and once on the tile floor in the kitchen. When she dropped it on the carpet, it was fine and she picked it up. But when she dropped it on the tile floor, it cracked open and fell apart. This is a great example of the relationship of force and time! (But not so great for her phone) Remember: impulses are the same because the change in momentum are relatively the same. When the phone dropped on the hard tile floor, the time the phone had to reach velocity zero was very small, making the force a lot bigger. In comparison, the phone that dropped on the carpet had cushion, which helped the phone not to break due to the increase in contact time. An increase in contact time helps to deplete force!

Therefore, drop your phone on surfaces that allow for more contact time!!

Forces that accelerate!!

Forces are fun!! When an outside, unbalanced force acts upon an object, the object accelerates. (When balanced forces act upon an object like rubbing your temples, the force stays at rest.) The inertia of an object causes it to continue until it is acted upon by another force.

This week we focused on forces that accelerate, which relates to Newton's second law: the acceleration of an object is directly proportional to the net force on an object; the acceleration of an object is inversely proportional to the objects mass. This means that when the force increases, the object's will acceleration will increase. As the mass increases, the acceleration will decrease, and as the mass decreases, acceleration is greater.

Let's take a look at an example!! After eating a tasty lunch with my sister, I got thirsty so she rolled me one of the drinks she bought. Knowing acceleration and the mass of the can we can find the force that my sister used to get it to me.

To find this, we would first make a free body diagram and then solve it using the only formula we know.... Fnet=ma!!

Yay forces!

Newton's First Law and Inertia!!

Unit 4 is all about forces! To understand forces better, we learned about the foundation of forces in motion: Newton's three laws. These laws were created by Sir Isaac Newton, a physicist born on January 4, 1643 in Woolsthorpe, England. His ideas became the basis of forces!

Let's focus in on the first of his laws, otherwise known as the Law of Inertia. Newton's Law of Inertia states that "objects in motion will tend to stay in motion unless acted upon by an outside, unbalanced force." This law could also be flipped by saying that "objects at rest will tend to stay at rest unless acted upon by an outside, unbalanced force. You might say, "What does that have to do with that thingy... inertia?" Well, in class we learned that inertia is defined as an object's capability to continue in the state it is in. We also learned that an object's inertia is directly proportional to an object's mass.

Okay, so what does this all mean? The typical thing for objects to do is to stay in the state that they were previously in. If no outside, unbalanced force interrupts this object, it will most likely stay in the state it was in.

Here is an example! (Sorry, it would be much better if I could upload videos but it doesn't let me. :( )

As the water bottle was being acted upon by an outside, unbalanced force (me pushing it), it broke its state of rest and began rolling (state of motion). When it hit the wall, it went from a state of motion to a state of rest. Why? Same thing! The wall is another outside, unbalanced force that changed the water bottle's state of motion to a state of rest. If the wall wasn't there, the water bottle would have kept on rolling along.

Newton's First Law helps us understand more about forces and how they work!!

More on Projectile Motion!!

While studying in Coffee Bean & Tea Leaf this fine Sunday afternoon, I noticed some physics going on! I payed for my drink and cornbread muffin and then went to sit down to study. When I put my wallet down, a quarter fell out of the pocket and fell to the ground. This reminded me of projectile motion!!





Now remember, there is one important rule to follow while using axes: the Vegas rule. In a previous blog post, I explained that the Vegas rule states that "what ever happens on the x axis, stays on the x axis" and "what ever happens on the y axis stays on the y axis". The only thing that is constant when trying to find either position, time, or range is that time is constant in both axes. If time is 3 seconds in the x, time is 3 seconds in the y.



My quarter is a wonderful example of projectile motion. The table that my quarter fell from was 2m from the ground. It fell at an initial velocity of 1m/s. We need to find where it's going to land to pick it up. Lets list our givens!!

With this information, we can use "dat" equation to find time (using info from the y axis)

d = 1/2at^2 + Vot

2m = 1/2(9.8m/s^2)t^2

2m = 4.9 m/s^2 (t^2)

0.408 = t^2

t = 0.64s

Fill in our givens table!

With this new info, we can find the distance it goes in the x axis!!

Use "dat" equation again!

d = 1/2at^2 + Vot

d = (1 m/s)(0.64s)

d = 0.64 m

If I wanted to catch my quarter off of the table, I would put my hands at 0.64 m away from the edge of the table. Great job!! Projectile motion is fun!

Relative Motion Once Again!!

Its been a while since we have talked about relative motion, so lets take it back a few steps! The most important thing to remember when dealing with motion is that it is always relative. Now you probably recall the upcoming question... "RELATIVE TO WHAT!" That's where things can go in all different directions!

For example, my two friends at the volleyball banquet tonight were walking together towards the food line. I snapped this first picture of them (lets just say they're walking at 5 m/s... that seems really unrealistic but I'm telling you, they were hungry!) They were able to carry a conversation because relative to each other, they were moving at 0 m/s. My friend in the blue dress started walking 3 m/s faster (8 m/s) to get to the line faster. To the girl in the blue dress, it seems as though the other is moving backwards (negative) when really she, herself, was just walking faster. Then, the same girl in the blue forgot her ticket! Oh no! She quickly turns around and walks quickly to her table at  5 m/s passing her friend (who is walking at the same speed). When they pass each other, it seems as though they are moving faster because all they can the blue girl can say is "WAIT FOR ME". She could only fit in 3 words because relative to her friend, she was moving at double the speed (10 m/s). When moving in opposite directions at the same speed, an object's speed seems to double!

Much more to learn in physics!!

2D Kinematics and Projectile Motion!

We have learned about the basics of vectors and how to use them, and this week, we learned a lot more!
First, we learned that equivalent vectors are vectors that have the same direction and magnitude! We also learned about the Vegas rule which relates to the saying "what happens in Vegas stays in Vegas". The Vegas rule states that all axes are independent: what happens on the x axis stays on the x axis, and what happens on the y axis stays on the y axis! During our last class this week we talked about the ball toss again and how it relates to the Vegas rule. The x and y axes are independent. We learned that the x axis is constaaaaaaaaant because it is moving at a constant velocity. The y axis is accelerating because a curved graph shows acceleration (fast slow stop slow fast). The picture below shows the y axis of the path of the ball my mom is throwing.

Vectooooooooor!

"I go by Vector. It's a mathematical term, represented by an arrow with both direction and magnitude. Vector!  That's me, because i commit crimes with both direction and magnitude. Oh yeah!"
- Vector. Despicable Me

This explains the definition of a vector! Excluding the "crime" part, a vector is an object with both direction and magnituuuuuuude! We learned that in adding and subtracting vectors, we measure from the tail of the first vector to the tip of the last. Lastly, we learned that a resultant vector is the answer (tail to tip).

In the picture below, my sister and dad are throwing a volleyball in our driveway. My dad is 12 feet infront and 5 feet to the left of my sister (red vectors). When represented with vectors, you can find the distance the ball traveled by finding the hypotenuse of the right triangle formed (green). Using the pythagorean theorem, i found that the ball traveled 13 ft. We did something similar in class with a football but I only have volleyballs!
There's a lot more to learn about vectors!

Passing Physics Onto My Parents!

It is amazing the amount of information we learned in just the first period of school! Who knows how much we'll learn throughout the rest of the year. Teaching my dad about physics was easier than I thought. He was pretty knowledgeable about physics, but I also taught him things that he didn't know! Although he knew about accuracy, precision, qualitative and quantitative data, and the standards of measurement, he stumbled on things having to do with kinematics, such as velocity, acceleration, and the equations. I taught him the different equations (dat, vat, vad, etc.) and he thought it was much easier to learn it that way! The graphing rules that I went over were also very new to him and he recited it for me twice. I think he understood them well! I showed him some of our past worksheets and quizzes and let him try some problems for himself. It feels good to know so much about physics and be able to share it with my dad!

Overview of the First Quarter!

We learned so much in physics in this short first quarter! The first thing we learned was observations. We learned that qualitative observations deal with the appearance and qualities of the objects. Quantitative observations deal with measurements. We also learned about Accuracy v. Precision. We learned that accuracy is something right on point, while precision is when you are consistent in your trials, but not necessarily accurate. Next, we learned about standards and why they are important. Standards are important so that everyone follows the same units and that everyone can communicate with each other.

We then learned about motion and the four words that are the most important when talking about motion:

"All motion is relative."

The next thing asked would be:

"Relative to WHAT?"

From the unit of motion, we explored more kinematics and how to solve problems using variables. We learned about speed, velocity, distance, time, acceleration, and displacement. The equations are listed in one of my earlier posts (dat, vat, vad)!

One of the most important things we needed to learn this quarter were the GRAPHING RULES.

1. The slope of a position v. time graph is velocity.

2. The slope of a velocity c. time graph is displacement.

3. The area under the curve of a velocity v. time graph is displacement.

We learned so much!!

These are examples of the graphs we needed to make and analyze in our labs this quarter.

Introduction!

Hi! My name is Codie Conching and this is my physics blog! I have been attending Kamehameha Schools since kindergarten and loved every second of it! When I'm not at school, you can find me on the volleyball court or spending time with family and friends. I always push myself to be the best person I can be and love to make others smile!

I have taken all of the science courses required for a junior at Kamehameha. In highschool so far, I took BSCS Biology and Chemistry and finished those classes with A's. I actually like science and think it is really interesting once I get into it. I found that since I am on the Honors math track, I grasp the equations and concepts a little easier. I am currently taking Honors Precalc, and it is challenging! In Physics, I hope to learn about how things work in my everyday life! I think Physics is on of the courses that actually reallt help you in life!! I also hope I learn how to problem solve more effectively!

This is a picture of two of my teammates and I this season. Volleyball is basically my life and I am so glad I got to be on the Kamehameha Varsity team this year!! This picture was taken by one of my friends after our game against Punahou thisn past weekend. I'm so proud of my team for sticking together and coming out with a good win! Love my team!! ♡

Acceleration and Kinematics

Acceleration can be defined as a vector quantity that explains the rate at which the velocity of a body changes with time. In class this week, we learned more about acceleration and velocity in relation to time and distance, and how to use the "Equations board...not bored" to find a variable.

This weekend, my team and I went to Las Vegas to play in a tournament. As we were taking off in our plane, I remembered about acceleration. The airplane can't just take off from its starting position or initial velocity (0 m/s). It needs to gain speed to be able to take off. The average speed needed to be met to take off is usually 150-170 mph. As the plane is being driven on the long runway, it is accelerating at a constant speed to reach the minimum speed to take off.

If we were trying to find the distance that the plane needs to go to be able to take off, and we were given the acceleration, time, and initial velocity, we could! All thanks to the Equation Board...not bored. With our information, we would pick either "dat", "vat", or "vad" equation to plug in our givens and find the variable we are looking for. In this case we would use dat equation!

d = 1/2 (a)(t^2) + (Vo)(t)

More Kinematics!

Physics deals with the things around us and we find it everywhere in our lives. Kinematics is a big part of physics! Recently we learned about velocity (how a velocity vs. time graph works) and acceleration. Velocity is the speed of an object in a given direction. Acceleration is the increase in the rate of something. We also learned the two other graphing rules:
1. The slope of a position v. time graph is velocity.
2. The slope of a velocity v. time graph is acceleration.
3. The area under the curve of a velocity v. time graph is displacement.

When driving to school, we need to get out of the valley to get onto the freeway. The speed limit on our roads in the valley is about 25 mph. When we approach the freeway, we start to accelorate our speed. While driving on the freeway, we stay at a constant speed of about 50 mph (speed limit 50). Getting off of the freeway, we decelerate to about 25 mph until we get to school.

Even though we are constantly moving while driving, it doesn't mean we are constantly accelerating. When we are driving it off the valley, we are going at a constant speed of 25 mph. On a graph, this would have a slope of zero because we are not accelorating, but staying constant. At the start of the onramp to the freeway until we get onto the freeway, there would be a positive slope on our velocity v. time graph because we are increasing our acceloration. On the freeway we would be at a constant speed of 50 mph (slope 0). Getting off of the freeway, we would slow down, causing our slope to go in a negative direction. On the final stretch to school, our slope would be zero because we would be traveling at a constant 25 mph.

Physics is all around us!

Kinematics!

We have learned so much about physics so far! We learned about relative motion last week and now we are talking about position, distance, displacement, speed, and velocity! We learned that position is where something is and distance is a scalar quantity referring to  how far away something is. Displacement is a vector quantity referring to how far out of place something is. For example, my dog, Hoku! She likes to play in the grass, running around in circles, and sometimes running after cats. When she goes outside, she leaves her shade under the tree and runs in circles (not doing many laps, shes kind of chubby), then stops and returns to her spot in the shade. Although her distance traveled may be high, her displacement is zero. This is because displacement refers to how far out of place she went. She started sitting under her shade and after finishing her workout, she returned to the exact spot she was in.

We also learned about velocity. Velocity is a vector quantity that refers to "the rate at which an object changes positions. Let's use Hoku for another example. When she runs for fun, let's say she runs at about 8 mph. But when she sees a cat and shes determined to chase it, she runs at a much faster speed, maybe 20 mph. If we were to graph this, we would find that the slope of the line for Hoku chasing the cat would be steeper than the slope of  her casual run. In class, we learned the first graphing rule:

"The slope of a position vs. time graph is velocity"

Because we know that velocity is the slope of a position vs. time graph, we can conclude that when Hoku is chasing a cat, she has a higher velocity than when she is going on a casual run.

Physics and Relative Motion

In Physics the other day, we learned about the basics of motion. There were four important words that we needed to remember:

"All motion is relative."

Today, I saw just that. During my car ride home on the freeway, I remembered about this blog post that we needed to write. I remembered that all motion is relative to something and that we can find it anywhere. I saw the cars in front, behind, and to the sides of me and thought about how they were moving in relation to me. Some cars were moving at the same speed as ours, and some were moving slower. I could tell that they were moving relative to me, but I knew that the ones going the same speed were moving different than the ones going slower.

The cars moving at the same speed as us were moving relative to the ground at about 60 mph (like we were). However, the two cars were not moving relative to each other.

Down the road, we saw cars going slower than us. As shown in the pictures to the right, it seems as though the cars are going backwards across the window of the car. In reality, they are moving forward but at a slower speed. This creates the illusion that the cars are driving backwards. The car is moving at a certain speed relative to the ground, but it is moving negatively in relation to our car.

There are many other examples of relative motion in the world - from watching the sun and clouds move across the sky, to jogging with your friend in the park. Physics is everywhere!

Physics From Our Childhood!

I never noticed it, but physics is a part of our everyday lives! From when we wake up in the morning to when we go to sleep at night, we experience physics right before our eyes. It has only been about 3 weeks in school and we have learned so many things about physics! We learned about the definition of physics, accuracy vs. precision, scientific notation, dimensional analysis, and the pendulum.

Today, I was driving home and passed the park next to MPI, like I do everyday. But as I looked closely, I say a young boy swinging on the swings and it reminded me of the pendulum lab that we worked on this week. Just like the pendulum, the swing has a suspended weight (the boy) swinging back and forth. In the lab that we did, we tested for the period (the time for one complete cycle), so I decided to do that too. The period for me was about 3 seconds! I was surprised at how easy it was to find physics in my everyday life!



 PC: My mama
Pendelum Swing. Digital image. The Pendulum Swings. N.p., 21 Sept. 2012. Web. 24 Aug. 2013.