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Physics Concept #1
By Juan Munoz and Jon Ibarguren
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Mr. Hiller for the title
Physics Concepts: Freefall Acceleration, Projectile Motion, Conservation of Energy, Newton's 2nd Law
The picture depicts a tennis ball in the air after being rolled off of a countertop. The ball had an initial force act on it (the hand of Jon Ibarguren) which pushed it across the countertop in the right direction. The friction force of the countertop was very minute, as the surface was recently cleaned to prevent sticky substances from increasing the friction acting upon the tennis ball. Regardless, the friction was present enough to cause the ball to roll as it crossed the countertop and approached the ledge. Once the tennis ball left the hand, a constant acceleration in the left direction opposed its initial velocity and inherently decreased such translational velocity as it rolled across the countertop. On the other hand, the ball's rotational velocity increased, as the friction caused the ball to roll and undergo constant rotational acceleration in the clockwise direction. Once the ball had left the countertop's surface, the horizontal translational and rotational velocities became constant, as there were no external forces acting on the tennis ball in those vectors. The ball entered freefall acceleration immediately after coming off the ledge, meaning it began accelerating 9.8 meters per second per second in the downward direction. The potential energy of the ball-Earth system was greatest at the point in which the ball was at the edge of the countertop. As it traveled downwards to the right, the potential energy of the ball-Earth system transformed into kinetic energy.
Word Count: 241
Physics Concept #2
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Mr. Hiller for the title
Physics Concepts: Newton's 2nd Law (Constant Acceleration), Conservation of Energy
A force on the skateboard was initially imposed when it was pushed by the hand of Jon Ibarguren towards the left direction. Immediately after the skateboard left his hand, friction from the groud acted upon the wheels of the vehicle. The frictional force caused two different accelerations in the wheels of the skateboard, both translational and rotational. The translational acceleration caused by friction pointed in the right direction, opposing the initial translational velocity of the wheels after release from the hand. In simpler terms, as the skateboard moved to the left, it began to slow down, later coming to a full stop. The kinetic friction of the wheels on the ground also causes a rotational acceleration of the wheels around their center axis in the clockwise direction. The wheels, rolling with friction, accelerate opposite to the initial rotational velocity of the wheels, as the entire skateboard slows over time. The dog, Riley, sticks to the surface of the skateboard due to static friction. As such, he moves in correspondence to the translational displacement of the wheels and board.
Word Count: 178
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