While playing tennis, there is actually physics related to the sport. Projectile motion is "the movement determined by an object's initial velocity and the constant acceleration of gravity." This works when there is zero air resistance. When I hit the ball, it starts traveling across the court at a certain velocity until it gradually changes due to gravity. The ball bounces on the ground, and then the other player hits the ball back. The horizontal velocity put on the ball never changes throughout the ball's flight. The time it takes the ball to bounce isn't affected by the amount of horizontal velocity the ball has, it is depended on the initial velocity and gravity put on the ball. This projectile motion may be more obvious when a lob is hit because the force of gravity acting upon the ball's initial velocity can easily be seen. The ball is hit up and falls back down because of its acceleration of -9.8 m/s/s, but the ball never changes its horizontal velocity until it hits the ground because there isn't a force changing it.
Sunday, September 21, 2008
Projectile Motion
While playing tennis, there is actually physics related to the sport. Projectile motion is "the movement determined by an object's initial velocity and the constant acceleration of gravity." This works when there is zero air resistance. When I hit the ball, it starts traveling across the court at a certain velocity until it gradually changes due to gravity. The ball bounces on the ground, and then the other player hits the ball back. The horizontal velocity put on the ball never changes throughout the ball's flight. The time it takes the ball to bounce isn't affected by the amount of horizontal velocity the ball has, it is depended on the initial velocity and gravity put on the ball. This projectile motion may be more obvious when a lob is hit because the force of gravity acting upon the ball's initial velocity can easily be seen. The ball is hit up and falls back down because of its acceleration of -9.8 m/s/s, but the ball never changes its horizontal velocity until it hits the ground because there isn't a force changing it.
Sunday, September 7, 2008
Velocity and Acceleration
This past summer I went to Las Vegas with my mom, sister, and Blake. While we were there, I rode the roller coaster at Circus Circus with my sister. This ride showed the physics of velocity and acceleration. Velocity describes the speed and direction of an object, while acceleration is any change in velocity over a period of time. The roller coaster's velocity was zero at the start of the ride. As we started moving up the track, it started to accelerate from rest to a slow speed and then maintained that speed for a constant velocity until we got to the top of the slope. After reaching the top, we accelerated again until we reached the peak velocity and couldn't accelerate anymore. We maintained this velocity throughout the ride until we started to slow down and experienced negative acceleration towards the end. The ride finally came to a stop for zero velocity again. We moved in the forward direction for the entire ride. We ended at the same starting position as the beginning, so there was no displacement during this ride.
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