Shadows?

This picture is of a wall hanging with a frame around it at my house. I noticed that the angle at which the light hit the honu created shawdows. These shadows are areas where there is an absence of light, so an abscence of color, thus the shadow is black. All the other areas are white because it reflects all the colors: red, green, and blue; simultaneously. In other instances, other objects appear to have different colors this occurs because specific objects reflect and absorb the different primary colors of red, green, and blue. For example, an apple appears red because it absorbs both the green and blue light, and only reflects red light. When two colors reflect at once, we detect different colors like the secondary colors which are magenta, cyan, and yellow. Our eyes see these colors because we have cones in are eyes. These cones are stimulated by green, blue, and red light. So when we think something is green its because our green cones are stimulated and if we see yellow, both our are red and green cones are stimulated.

Can Humans Be Magnets?

I was watching TV the other day and this old man attracted metal to his body. Can humans be magnets? Of course not, but they did not tell us what the cause was of this man's unique ability till the end of the segment. The reason was that he had very smooth skin and he could produce a lot of static electricity. When the metal came into contact with his body it would create a vacuum, so the metal would stick, and not want to come off. But at first, this man deffinitely made me think that he was a magnet! :) But anyways this deals with physics because of the magnetic part. Magnets are things or objects that have a magnetic field and exerts a magnetic force. They have two poles; a north and a south pole. Like poles repel each other, while opposite poles are attracted to each other. When these poles either repel or attract each other they are creating a magnetic field without even touching each other. Unfortunately the man was not magnetic but he's the closest human to being a magnet. ..forgot to mention, his three grandson's have the same ability. (they think the trait skips a generation.)

Electromagnetic Spectrum

The other week my softball team had a team bonding. Part of the team bonding we had a little scavanger hunt where we took pictures with random things and people. I think one of the pictures we had to get was with a rainbow. I realized that the colors found in the rainbow are part of physics because it is part of the electromagnetic spectrum. This spectrum is types of electromagnetic radiation organized by it frequency or wavelength, which each have their own electric and magnetic field. In the spectrum, it includes radio waves, infared, UV, x-rays, gamma rays, and visible light. The visible light is what consists of the rainbow because visible light includes all the colors and white. In the electromagnetic spectrum, as you move to the right of the chart, the frequency of the wave increases as the wavelength decreases. Meaning that the frequency and wavelength vary inversely.

Moment of Inertia: Dance Moves

I was watching America's Best Dance Crew and I noticed that Quest Crew had some pretty cool dance moves. I saw that one of the dancers applied physics in terms of moment of inertia and angular momentum. Moment of Inertia is determined by the mass and the distribution of the mass and is basically a measurement determining if an object is easily or not easily able to be rotated. So the formula is I= mr^2. So a object that can easily be rotated and likewise easily to be stopped rotating has a small moment of intertia and vice versa. So something can be easily to be rotated resulting in a small moment of intertia if most of its mass is located close to the axis of rotation. In ABDC, the dancer is doing a headspin and he is rotating quickly when his arms are in because he has a small moment of inertia. However, he puts his arms and legs out as he spins and he appears to slow down, this is a result of the change in the distribution of mass, making his moment of inertia to increase. And once again he brings his arms in again and he appears to speed up because he is easier to be rotated. This dancer also demonstrates angular momentum and it conservation. Angular momentum is determined by multiplying the moment of inertia and the angular speed. The momentum is conserved throughout because when he brings his limbs out his moment of inertia increases, but his angular speed decreases and when he brings his limbs in his moment of inertia decreases and his angular speed increases following the law of conservation of momentum. Hope you enjoy the short clip!

The Perfect Push-up

My dad has these workout things that you see on television: its called The Perfect Push-up. These handlebar looking devices are used to help you complete a push-up with proper technique, I suppose. (I've tried it and its not much easier than a normal push-up!) But I realized that these push-up things apply the concep to of torque.

Torque is a force that either causes or opposes rotation. Torque can be calculate by multiplying the lever arm, the distance from the axis to the point of the force, by the force exerted. In this case, a force causes rotation of the push-up devices which eases the tensions on your joints as you do a push-up. In this example, these handlebar things have a low moment of inertia. Moment of inertia is the measure of the resistance to the angular accleration. Moment of inertia equals the net torque divided by the angular acceleration. With the perfect push-up the moment of inertia is low because the net torque is low due to a small amount of force for them to rotate and a high angular acceleration because they rotate quickly. This low moment of inertia also contributes to the ease of the handlebars to make the push-up smooth and comfortable.

Crash!

At the end of summer, my brother got into a car accident. And this crash actually totaled our car. Luckily he did not get hurt, but I realized that his crash was physics related. He was on a freeway on-ramp in Aiea. This on-ramp was sort of like a loop (i think it was like 270 degrees). As he was turning, his car skidded and hit the railing. Apparently, many people had crashed in the same place before and there was many skid marks on the ground. (Someone five minutes before my brother had done the exact same thing!) This accident has to do with centripetal acceleration and centripetal force. Centripetal acceleration is the change in direction in a circular motion, and so velcoity is never constant. (centripetal acceleration = v squared/r) Centripetal force is the force that causes the circular motion and force is always directed toward the center. (centripetal force = m(v squared)/r) Centripetal force can represent different things in different situations. For example, centripetal force can represent the normal force, friction, or a combination of both. In my brother's example, the centripetal force was friction, but with the evidence of skid marks, it can be concluded that there wasn't enough friction, so there was not enough centripetal force to keep him in a circular path, which ultimately resulted in his crash. Also, his speed could have also contributed to the crash because in the centripetal force equation, a higher velocity directly results in a higher centripetal force required to stay in a circular motion.

Center of Mass: Basketball Techniques

This past weekend was the girls Iolani Classic. Teams from both coasts came to play, including the 1st, 2nd, and 4th nationally ranked teams in the nation. In the mechanics of playing basketball, the physics concept of the center of mass is used. While playing either on offense or defense, your center of mass is important. The center of mass (also the center of gravity) is our average location of your mass. At this point, it represents the mass of the entire object. Your center of mass can change and it does not have to be within the object. Playing on offense you want to stay lower than your defender so that you center of mass is lower, which results in quickness and speed. On the other hand, if you are on defense, you want to have a lower center of mass so that you can react faster to your opponent. The concept of center of mass is also very important in shooting the basketball. The proper mechanics in shooting includes feet pointing to the basket, shoulders square, and jump straight up, these all provide for a balanced body. If you follow these mechanics your shot should be good because your center of mass should be in the middle of you body (belly button area). As you can see in this picture, the player (school: Westlake) is trying to shoot the ball but her body is bent in like a "C". This is improper shooting technique. Her center of mass is outside of her body behind her torso becasue her arms and legs are behind her body. This creates a difficult shot becasue her body is unbalanced due to her change in center of mass.