Average time (at the end of each section)
Results: (the following tables and graphs were calculated using average times)
Velocity Time Table and Graph
Kinetic Potential Energy/Velocity Table and Graph
Gravitational Potential Energy Table and Graph
Discussion:
The ball bearing was initially stationary and did not move – Newton’s First Law of Motion explains that a stationary object will remain stationary unless a force is exerted upon it. The ball bearing began moving down the first incline after being released due to the Earth’s gravitational force acting upon it, giving it gravitational potential energy. During a rollercoaster ride, gravitational potential energy converts repeatedly into kinetic energy and back – as potential energy converted into kinetic energy, the ball accelerated down the slope as gravity pulled it towards the earth’s centre.
Therefore, the start of the track must be the highest point of the ride to build up enough potential energy and the lowest point of the rollercoaster is when there is the most kinetic energy. If there was a point in the rollercoaster that was higher, the ball bearing would not be able to travel up the hill as there would not be enough energy to do so. The conversion into kinetic energy increases velocity which is based on height, meaning velocity would be highest with more kinetic energy (travelling downhill and at low points of slopes) and the weakest with more gravitational potential energy (travelling uphill and on slope high points).
The Law of Conservation of Momentum can be explained by the following: the total momentum of an isolated system, where no external forces are acting upon it, will remain constant. This means theoretically, the amount of energy the ball bearing had when it was released must equal the potential and kinetic energy when the ball bearing travels up and down on slopes as well as the amount of energy the ball bearing finished with. However the ball bearing will have less energy at the end of the track as opposed to the beginning as it would have lost energy due to friction and friction is an external force.
We also had to make minor modifications after trialling our rollercoaster as we encountered a few problems. We found the ball travelled too fast down the slopes and built up so much kinetic energy it flung itself off the second slope. To counter this, we should have made the inclines less dramatic or increased the distance of the uphill slopes but we simply released the ball 5cm down from the beginning of the track and readjusted the curve to make it less steep. This meant there was less gravitational potential energy and more distance for the ball to travel.
Other changes that could improve our rollercoaster track include lengthening the second uphill slope or altering it to make it higher as the ball built up too much kinetic energy on the first downhill and travelled too quickly uphill, resulting in flying off the track. For a smoother run, we could have straightened the uneven bumps in the tracks by measuring the original track dimensions more accurately or applied masking tape on the curves and dips to reduce friction and the amount of energy lost by the ball.
Conclusion:
The object had the greatest velocity at the lowest points of the rollercoaster and the lowest velocity at the highest points of the rollercoaster. Therefore, there is a relationship between the height and velocity of an object, and the results supported the hypothesis.
References:
“Energy Transformation on a Roller Coaster” – 1996-2010 The Physics Classroom. Accessed 23 August 2010.
“Run a safe roller coaster” – Accessed 24 August 2010
