Physics of a Ball Dropping
Autor: micko69 • December 9, 2017 • Research Paper • 1,234 Words (5 Pages) • 718 Views
Physics of Bouncing a Ball
[pic 1]
Introduction
Officially invented in 1891 by Dr. Naismith in Massachusetts, Basketball is a highly-popular sport played by two teams on a rectangular sport. In which, the objective is to shoot a ball through a hoop, which stands 10 feet (~3 meters) from the ground. Whenever someone is successful in doing so, they are awarded points, depending on how far back the person shooting was. Whichever team scores the most amount of points, within the allotted time, wins. In ~1950, the game added a new mechanic known as “dribbling”, which is simply the continuous bouncing of the ball. Now, with the addition of “dribbling”, came standardisation of ball pressure (50-60 kpa) to allow for consistent behaviour. But, how exactly does air pressure affect the ball’s behaviour? This experiment is being done to observe, record, and investigate how air pressure affects the bounce height of a ball. It is hypothesised that the basketball will bounce higher when filled with more air, but only finitely. As more pressure is added, the bounce height should appear to increase at a much higher rate, until it would level out as in the logarithmic model (1).
**REASONS FOR HYPOTHESIS**
Variables
Independent:
Dependent:
Controlled:
Apparatus
- Camera
- Ruler (1 Metre)
- Basketball
- Air pump
- Air pump accessories (nozzle, pin, etc.)
Procedure
- Setup the air pump by fitting
- Deflate the basketball until its pressure equals 40 kpa
- Place a ruler, vertically, against a flat surface (wall, table etc.)
- Drop the ball from a height of ~1 metre, with the ruler in view, while recording
- Repeat step 3, three times
- Increase the ball’s air pressure by 20kpa
- Repeat steps 4-6 another three times
Results
Air Pressure | Energy1 (J) | Test 1 | Test 2 | Test 3 | Average | Energy2 (J) |
40 kpa | 5.72 | 60% | 61% | 60% | 60% | 3.43 |
60 kpa | 5.72 | 69% | 68% | 67% | 68% | 3.89 |
80 kpa | 5.72 | 73% | 73% | 71% | 72% | 4.12 |
100 kpa | 5.72 | 74% | 75% | 74% | 74% | 4.23 |
[pic 2]
Discussion
Throughout this entire investigation, the purpose was to prove that the ball would bounce higher when more pressure was added to it. **HOW IT IS RELATED TO BASKETBALL**
**OVERVIEW OF RESULTS**
To explain the physics behind the vertical bounce of a ball, the process must be broken up into several distinct stages. First, is the stage of suspension, in which the ball has all of its gravitational potential energy; as expressed by “mass * gravitational acceleration * height” (mgh). At this point, the ball has 5.72 joules (0.583*9.81*1) of stored energy. Next, the ball begins to fall downward under the influence of gravity, converting GPE (gravitation potential energy) into KE (kinetic energy). The velocity (v) and acceleration (a) are pointed downwards as well (2). In the third stage (3), the ball makes initial contact with the ground. However, at this point, it has barely touched, so it is still under the influence of kinetic energy. Now (4), in the fourth stage, the ball has begun to slow down and has deformed enough that the acceleration is now pointed upwards. This is a result of it pushing against a surface with a force greater than its own weight. At this point, kinetic energy has been converted to EPE (elastic potential energy). After it has reached the maximum deformation (5), the ball’s velocity is zero and about to rebound. Then (6), the ball’s upwards velocity begins to increase, while gradually returning to its original shape. But, it is still deformed enough that it’s pushing against the ground with a force greater than its own weight. Therefore, the acceleration is still pointing upwards as well. In the next stage (7), the ball is barely touching the surface, akin to stage three. The velocity is still pointed upwards, as it is still in the rebounding stage. However, as it is still being acted upon by gravity, the velocity is decreasing. With this, EPE has been converted back to kinetic energy. As the ball gets higher and higher, more energy is stored as GPE. However, it will never return to its original height, as energy is lost throughout the entire process. First, energy is lost because air resistance, when the ball collides with air molecules; creating heat through friction. This also occurs after the ball rebounds. Another way energy is lost, is when the ball deforms and transfers to sound and heat. Evidence of this, other than hearing the ball bounce, is that the ball would return to its original height. But, how does pressure affects the bounce height of a ball?
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