Pressure

We recently got a sprinkler system for our house, so I was wondering how it works. Of course, I thought, there must be physics involved. So then came the idea for my blog: to find out how our sprinkler system works. After a whole year of physics, I was able to deduce that the water is pumped to the sprinklers under pressure, and I was right. Sprinkler systems uses jet pumps to get the water from a source to the sprinkler heads. The pump pushes the water up from the ground through the underground pipes. Sounds a lot like what we learned in physics about pressure. Pressure is equal to force over area, and since the area of a sprinkler system doesn’t change, the force has to be increased to increase the pressure and get water flowing. I’m glad that pressure is able to water our yard but now I’m thinking that we need it to tell us when it will rain so that our sprinkler system doesn’t go off when it is raining. Speaking of pressure, I think we need a barometer! Barometers measure atmospheric pressure, the pressure created by the weight in the atmosphere. Therefore, a barometer could probably tell us when it will rain because there will be more pressure in the atmosphere.

Driving

I have been learning to drive on the road and noticed some things that are physics related. For example, when you keep your foot on the gas pedal, the car keeps accelerating. The harder you push on it, or the more force you apply to it, the faster it goes. In addition, there are three mirrors that you use: the rear-view mirror and the side-view mirrors. Each of them use reflection to help the driver be more aware of what’s behind them, but they are different types of mirrors. The rear-view mirror is a plane mirror while the side-view mirrors are convex mirrors to help the driver have a wider field of vision. The picture to the left is a picture I took while I was on a road trip. You can see the plane mirror in it. Last but not least, there is a bit of uniform circular motion when you drive because when you turn the car, you want to keep it at the same speed so that you can predict where the car will go. That’s pretty much it for the physics that I’ve realized so far while driving.

Rotation in Tennis

My week was pretty mundane, however, I did practice tennis and remember some movements involving physics. This week, I worked on hitting the ball out of the air. This is hard to do because you need to rotate your body to generate speed and get the ball to go over the net. I realized that rotating your body makes it easier to hit the ball hard rather than just slapping at the ball because you produce angular momentum as you are rotating towards the ball. If you just try to hit the ball by using you arm, your arm and your shoulder will get sore because you aren’t following the laws of physics by using torque. I think rotational forces are stronger than linear ones, which is why you should rotate your body but also lean forward as you hit the ball because you need both angular and linear momentum to get the ball to go forward and hit the ball hard. This is a pretty simple concept in tennis, but it requires hard work to rotate and hit through the ball every single time. That’s why you have to go back to the basics and think about the rules of physics.

Malasadas

Okay, I had a pretty tiring weekend so far. I mainly just played tennis and hung out at the fair. What I remember most from last night was making malasadas, so I'm going to try to explain the physics involved in making malasadas. First, to make sure your hands don't stick to the dough, you need to put oil on them. Next, when you get the dough, you have to massage it and spread it out to get the bubbles out. Then, to actually make the malasadas, you need to grab some dough, make a ring shape with your fingers on one hand, and use the other hand to push the dough up through your fingers. You need to make sure the dough is smooth on top so that the malasadas cook properly. Finally when the malasada ball looks smooth and round, you pinch off the bottom to get it to the size that you need it to be. I think by learning the physical aspects of making malasadas, I was able to make the malasadas more effectively and more tasty.

Hot Tub Jets

I went to a pool party yesterday and sitting in the hot tub made me wonder how a hot tub actually works. So, I looked it up on the internet. It turns out that there is a lot of physics involved in the functioning of a hot tub. I learned that a hot tub works by pulling water through a system of pipes and through a heating device before ejecting the water into the tub. Some kind of suction or pressure filtration system draws the water from the hot tub and into a filter. The water is checked for impurities, goes through a pump, and finally, the water gets filtered. After getting filtered, the next step in the process is heating the water. The water is heated to a certain temperature, and there are flow switches and an overheating switch that are used to control the temperature and flow of the water. The water then passes through pipes before reaching the jets. Today, the jets of hot tubs use air induction, which allows warm water to mix with air, to make the stream of water from the jets extra strong. Now I know the sort of physics that goes on in producing the stream of water from hot tub jets.

Wave Interference Patterns

When I was taking a bath the other day, I squeezed the water out of my hair in the bathtub and noticed interference patterns forming from the droplets of water. There were regions of dark and bright interference. I realized that I could create my own constructive and destructive interference patterns. Today, I decided to try creating them again in my sink. In the picture, you can see waves of constructive and destructive interference. They remind me of waves in the ocean. The higher points (crests) are constructive interference and the lower points (troughs) are destructive interference. The shape of the medium can be determined by the sum of the amplitude of interfering waves. Constructive interference occurs when a crest meets a crest, creating yet a bigger crest. Destructive interference occurs when a crest meets a trough or vice versa, creating very small peaks. From doing this little experiment, I learned first hand how waves are created and what constructive and destructive interference look like.

Contact Lenses and Reflection

I didn’t really experience anything exciting that was physics-related this week; however, when I was putting in my contacts this morning, I remembered that we are learning about lenses. I always wanted to know how contact lenses worked ever since I got them because my vision improved dramatically when I got contacts. I’m nearsighted, which means that my eyes can’t focus on far away objects because the light rays converge in front of the retinas in my eyes. Therefore, I need diverging lenses in order to help me see faraway things because diverging lenses make the light rays diverge a little more so that they can converge farther away, at the retinas. When I was looking at my contacts, I also realized that they are fatter at the edges than at the center, just like our textbook says about diverging lenses for nearsightedness. When I was taking the picture of my contacts for this blog, I also realized that I was in front of a plane mirror, and since we are also learning about reflection, I decided to incorporate the image of my contact lenses in the picture.

A Convection Oven

I was using a convection oven to cook French bread pizza for lunch today, and it occurred to me that I never knew how it works (besides that it cooks my food faster than a regular oven). What are the physics behind it that power it and heat up my food? I decided to look that up and find out for myself. I found out that “convection” is the movement of molecules, and the process of convective heat transfer occurs through diffusion, the random movement of particles. Heat transfer works by the transition of thermal energy, and we learned that heat always flows from the hotter object to the colder one. Forced convection is the heat transfer of a fluid that is not induced by a natural heating force. This is the type of convection that powers a convection oven. In a convection oven, a fan is turned on and spins quickly so that the heat it produces is used to heat up the food. In this case, the heat from the fan is transferred to the food and heats it up because the food is colder than the fan. Who knew you could learn so much about physics by just making your lunch.

Bobsledding

Last night, I was watching a little of the Olympics. Bobsledding came on and although I’m usually bored by bobsledding, I decided to watch it because a U.S. team was about to go. The first U.S. team was kind of disappointing because they tipped over on their side at the end, costing them big time. However, the last team was another U.S. team, and they did outstanding, so I think they got gold. They apparently got first by 0.04 seconds, a miniscule amount of time. When the announcer was explaining how they went so fast, physics popped into mind. He said that what go them the fastest time was that all the bobsledders on that team kept their heads super low. This was the factor that sped them up because there’s a natural G-force that is trying to pull them up, but they did a good job of opposing that force by staying so low. By keeping low, they also cut down a lot on their air resistance, which helped to cut down their time. I learned something about bobsledding while the announcer explained the “G-force”. I knew that the bobsledders kept low to avoid air resistance, but I didn’t know that a G-force was also pulling them up at the same time, making it harder for them to go as fast as they can.

Winter Olympics

Since I've been watching the Winter Olympics as much as possible, I realized that there is quite a bit of physics involved in many of the events of the Winter Olympics. In fact, in some of the events, physics plays a major role in how well you do; one little mistake in your movements can cost you a medal. When I was watching Apollo Ohno in the speed skating final yesterday, he said that if he hadn't had that one little slip, then he could've won gold, but he came up short and got bronze because of that one mistake that slowed him down. In addition, in all the downhill sledding sports such as luge, bobsled, and skeleton, any little movements away from the center can cause air resistance and slow you down. The announcers even said that a little mistake at the top can be more costly than a smaller one at the bottom of the track because you don't have much speed yet at the top. While watching ski jumping, I was wondering why the skiiers bodies get so paralled to their skis, and I deduced that there is physics involved in this technique. I thought that they get as parallel to their skis as they can because it causes less air resistance, allowing them to jump farther. Overall, the Winter Olympic games involve a lot of air resistance, velocity, and momentum.

The Physics in Rides

I was so busy this past weekend that I had no time to go to the Punahou Carnival (which, I suppose, can be a good thing since I go to Iolani). However, thinking about the carnival made me get the idea of writing my physics blog about the physics in carnival rides. For instance, the Swings and the Ferris Wheel are good examples of uniform circular motion. On both rides, you sit in something as it goes around in a circle at a constant speed but constantly changing velocity. Pharaoh’s Fury is an example of a ride that moves like a pendulum. It goes back and forth, has its greatest velocity at the bottom, and its least velocity at the top of either side. Ring of Fire is a roller coaster, which demonstrates acceleration. After the roller coaster is released from rest at the top, it accelerates at a constantly rate downward and then decelerates at a constant rate back to the top. These are just a few examples of physics is carnival rides, but all rides have some kind of physics involved in them.

Power in Tennis

I didn’t experience anything interesting this weekend, so I have to talk about tennis again. Yesterday, in my tennis lesson, I learned how to hit through the ball more. When my tennis coach says to “hit through the ball”, he means to use your body more to hit a heavier and deeper ball. The most important thing I learned was that by leaning forward when you hit the ball, you can put more power on the ball, which makes it heavier and faster. Leaning forward also gives you more momentum while you are hitting the ball. In addition, it keeps the ball from flying up, which gives it a more direct, straight shot. Another important thing I was practicing was bending down low and staying low while I hit the ball. This also puts more power on the ball because you get more power by using your legs. Last of all, another key to hitting through the ball is setting up quickly and then rotating your body. This creates torque and also puts more power on the ball. All in all, keeping physics in mind while you are playing tennis can really make a difference in how you hit the ball.

Friction in Tennis?

I bought a new pair of tennis shoes that I had never tried before. Of course, all shoes are built differently, so they are going to feel differently too. This shoe in particular rises up high by my ankle and cuts into my foot. I discovered that in combination with this design, the shoe is also kind of stiff and hard in that area. This was not a good combination and resulted in rubbing my skin raw. I felt a pain just in front of my ankle, and I deduced that due to the force of friction between my shoe and my skin, the shoe was rubbing my skin off. I decided that to cut down the friction between my already raw skin and my shoe, I should wear higher socks and put tape over my skin to protect it from the force of friction. Similarly, when I used my coach’s racket one time, his grip was tough because it was made of leather, and it gave me a blister. This is also largely due to the friction between the grip and my hand. My hand hurt the most when I was hitting forehands because that’s when I turn my hand on the grip the most, causing more friction to occur. I never knew there could be so much friction in tennis, and I unfortunately discovered this by getting sores on my hands and feet.

Ice and Water

I witnessed a simple but cool event of physics the other day. My mom always drinks water without ice because she doesn’t like her water being too cold. I, on the other hand, like ice in my water, so when she brought me a cup of water without ice, I asked her to put ice in it. Normally, you would put the ice in first, but since there was already water in the cup, she had to put the ice in after. When she put the cup under the ice dispenser and ice started coming out, water started splashing all over. One can figure out why this happens by using simple physics concepts. The force of a heavy solid, ice, falling on water, a fluid, creates the splash. The ice displaces the water and makes it come up. Ice is lighter and less dense than water, however, if you put it in the cup after the water, the water splashes up because the ice has a lot of kinetic and potential energy when falling from the dispenser into the cup. So by analyzing an event using physics, one can figure out why something happened.

Tennis Strings

In tennis, the type of string, the tension, and the stiffness of the string all play an important role in how you hit the ball. I use two different types of synthetic gut strings, which are a harder type of string than regular gut so that the string lasts longer. I was experimenting with hitting with a softer string but with a higher tension because I wanted to hit the ball harder and still keep it in the court, however, my strings were breaking too quickly. I figured out that a softer string breaks fast because its weaker and having a higher tension also makes it break faster because the string is more stretched, so it breaks faster. I also saw that with the softer string, you could see the string fraying more before it actually broke. This is due to its weak physical qualities, and that’s why it also breaks faster than stiffer strings. I then experimented with my coach’s racket, which has really stiff strings, but my elbow started hurting. I found that really stiff strings don’t absorb vibration very well, so it affects your arm more and can cause more injuries. My coach told me that I shouldn’t use too soft or too stiff strings because I would either break them too quickly or injure myself, so I went back to a string in between the two. I never realized all the physics involved in stringing a racket. The tension, stiffness, and type of string are all important qualities in the strings of your racket.