Torque

I found a glider in my house closet and realized that by spinning the glider and letting it go, I was demonstrating a concept called torque.

Torque is a measure of how much a force on an object causes it to rotate. How much torque depends on the amount of force and distance of the lever arm (from where the force is applied to the axis of rotation).

In the case of the glider, force was put on the glider to make it spin along its axis of rotation. The pivot point is at the top of the glider. The distance from the top of the glider to your hands is equal to the lever arm.

Torque is maximized if the distance of the lever arm is huge, there is a massive force, and force is perpendicular to the lever arm.

Tennis Collision

To illustrate the law of conservation of momentum, I took pictures of a collision between two tennis balls. Conservation of momentum states that in an isolated system, the total momentum is conserved.

During the collision of the tennis balls, momentum transfers from one ball to another. The combined momentum of both balls is constant meaning that the loss in momentum of one is equal to the gain in momentum of the other balll.

Coliusion of the tennis balls is also an example of elastic collision because the kinetic energy before and after the collision is equal to each other.

Momentum is conserved in both inelastic and elastic collisions. Momentum is equal to mass times velocity. Therefore, in the case of the tennis balls, the addition of momentums initially of the balls must equal to their addition of momentums after the collision.

Dizzy Spinning

I was busy this whole weekend with helping out at the Penny Carnival my church held on Halloween night and attending a Spoonful of Sugar meeting on Saturday at school that I didn't get the chance to take pictures involving physics.

For this physic's journal, I'm going to use a picture that my sister took while she went to Singapore. In the picture, she is by a spinning top. As the top is spinning, it is undergoing physics.

The top rotates along a principal axis. Spinning around the rotation axis gives the top an angular momentum and this angular momentum will remain constant unless torque is added to the top. The process in which the top's end rotates along the vertical axis is called precession. The top precesses in the direction of the torque exerted by its weight. As the top slows down, its precession increases. The top then begins to wobble and then falls down. Gravitational torque produces precession. Torque is a vector quantity and its direction is in the change in angular velocity.

Hopefully, I will have more physic related pictures by next week. Other than that, after searching up the physics of a spinning top, I learned some new physics terms which I know we will come across in the future.

Physics!

Physics so far has been interesting but challenging for me. It is cool to know that everything around me is related to physics in some way. I enjoy the labs and classwork we do to enforce the material we are learning. However, I find that even though I do understand the concepts, solving physics problems is a bit of a challenge. Sometimes on homework problems, I don't know how to approach a problem or where to begin.

I want to do well in this course and I know it is going to take a lot of work to do so. As the first quarter draws to an end, I'm a bit hesitant about where my grade is going to fall. Not only that, but as the year continues on, physics is going to be more difficult. My goals for the rest of the year in physics is to study hard, try to improve in my quizzes and tests, and come in for extra help if I don't understand something.

As of right now, I feel like I can do better in terms of my performance. The image that conveys my state of mind in physics is a growing plant. At first a plant is hard to grow because it needs the right amount of nutrients and sun-light. I am in the beginning stages of a growing plant. Physics may be difficult at first, but it will get better by setting goals for myself and gradually making improvements. At the end of the year when I look back to the beginning of the year, I'll see how much I've grown. Despite the challenges, physics is fun class.

Round About I Go

One of my hobbies that I enjoy doing is riding my bike. If I have free time, I usually ride around my neighborhood. I have to say that it's one of the best ways to exercise. The breeze and sunshine just make riding so much more fun. You enjoy the scenery while burn some calories.

Try riding your bike this week, it definitely is worth it.

There is physics in riding a bicylce. First of all, a gravitational force pulls the bicycle to the earth. Gravity has an effect on the rider and bicyle. If travelling uphill, gravity works as a force against the rider (force equals mass times gravity) so the rider must put more force on the petals to keep the momentum going. Momentum is equal to mass times velocity. The acceleration of a bicycle is called centripetal acceleration. The wheels of a bicycle move in a forward direction due to centripetal acceleration pointing toward the center of the wheels. More force is needed to move a smaller wheel a certain distance compared to a larger wheel. The weight of a bicycle also determines how much force needs to be applied to move the bicycle. The more the bike weighs, the more force is needed to work the petals of the bicycle. This is one reason why cyclists who compete in bicycling marathons have bicycles that weigh very light. Light bikes allow them to use little force to travel a greater distance. Another concept of physics found in bicycling is friction. Breaks increase the amount of friction on the wheels and cause the bicyle to slow down or stop. Smooth ground surfaces have less friction which create less force needed to accelerate the bicycle.

Every aspect of bicycling contains something related to physics. Hurrah for physics!!!

Jungle Fun!

On Saturday, I went to Jungle Fun at Alamoana Center with my sister. We wanted to watch people play games and cruise around. It was pretty crowded there. I haven't been to Jungle Fun in quite a while, so some of the games were new. We didn't intend to play any games so we left after staying there for ten minutes or so.

Before leaving, my sister pointed out a cow attached by a string to the ceiling flying around in circles. The cow's circular movement had something to do with physics so I decided to take a picture of it.

As the cow moves in a circles, it is accelerating because the velocity is constantly changing direction. Acceleration is caused by a force acted upon the object. According to Newton's second law of motion, an object experiencing acceleration must be experiencing a net force. In the cow's case, centripetal force causes the cow to move in a circular path. Centripetal force is known as the center seeking force because the force is directed toward the center of the circle. Without this force, the cow would not be moving in a circular motion, but in a straight line. Newton's first law of motion or law of inertia states that objects in motion tend to stay in motion with the same speed and the same direction unless acted upon by an unbalanced force. Therefore, centripetal force is the unbalanced force needed by the flying cow.

If an object has a small mass, then the centripetal force is small. If the string that the object is attached to is short, then more centripetal force needs to be applied. The cow flying in circles is a product of physics due to centripetal force. That is so cool!

Playing Frisbee

Over the weekend, my sister and I played frisbee in our frontyard. In this picture, my sister is throwing the frisbee to me. As she releases the frisbee into the air, the air moving above the frisbee flows faster than the air underneath it. Due to the Bernoulli principle, the lower air pressure on top of the frisbee compared to the pressure underneath the frisbee causes the flying disk to rise.

Newton's Third Law, which states that for every action there is an equal and opposite reaction, is also shown in the movement of the frisbee. While the frisbee moves, it forces air down (action) and air forces the Frisbee upward (reaction).

Once in the air, the frisbee remains stable because of its angular momentum or spinning. Gravity also has an affect on the frisbee by accelerating its mass to the center of the earth.