Wednesday, 25 May 2011

Physics lab investigation

Our hypothesis was that the higher we held the ball at the beginning, the higher the velocity would be when the ball hit the ground. This is because it would have more time for gravity to bring it down, and it could accelerate more with more time. Also, we predicted that the golf ball would have a greater impact velocity and force than that of the ping pong ball because its mass was so much higher. We measured an average drop time of .24 seconds for the ping pong ball, as well as a velocity of 4.1 m/s/s. The golf ball showed an average drop time of .38 with a velocity of 3.6 m/s/s. The ping pong ball had an average drop time of .66 seconds and an average velocity of 3.03 m/s/s. The gold ball had an average drop time of .67 seconds and an average velocity of 2.99 m/s/s. These results were much closer together than in our first test, as well as slower to the ground and with strangely lower velocity. For our final test, which occurred at a height of three meters, the ping pong ball dropped in an average of .81 seconds and with a velocity of 3.73 m/s/s. The golf ball fell in an average of .82 seconds, with an average velocity of 3.66 m/s/. These results were very similar to the second set, and with an average lower velocity than the first test.
Our test with the motion sensor was somewhat of a failure as compared to the much more efficient manual test. The equipment was inaccurate with its recordings, and the graphs it made are difficult to read and understand.

Half of our hypothesis was correct throughout this experiment, and we had some odd results. We were supported in our prediction that the golf ball would hit the ground with greater force than the ping pong ball, due to it's increased mass. (The gold ball weighed 45.66 grams, while the ping pong ball was only 2.5 grams. This means that gravity would have a greater effect on the golf ball than the ping pong ball, and therefore it would hit with more force than the lighter sphere.) Our round of single meter tests were outliers from the other two tests, those of which had the results we had predicted in our hypothesis. For this reason, it is safe to conclude that there was human error in the recording of our data for that round. As for the two rounds where our predictions were supported, the velocity gradually increased as the drop hight increased. For the reason that the balls were higher prior to the drop, the three meter testing session had higher average drop times than in the two meter session. The section of our hypothesis that was not supported was our prediction that the golf ball would fall faster than the ping pong ball. Looking back, this could have been explained by Newton's Second Law of Motion. Objects with higher mass take longer to accelerate than those with less mass. Judging by this, the ping pong ball would have accelerated more quickly than the gold ball. However, gravity is known to accelerate all objects at a speed of 9.8 m/s/s, which could explain how extremely close our results were for both balls. Human error clearly occurred in our first test, judging by its outlying results. Mechanical error occurred with the inaccurate motion sensors. This experiment was a good representation of the power gravity can have over objects of different masses.