MSE 24 Experiments: – Does a rider's weight make a difference? – Introduction
MSE 24 Experiments: – Does a rider's weight make a difference? – Introduction
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mse24
MSE 24 Spring 2013 seminar presentation [presentation]On Github gruiz17 / mse24
MSE 24 Experiments:
Does a rider's weight make a difference?
A presentation by Gabriel Ruiz, Grace Shen, and Timothy Park.
Introduction
On the fateful and heated summer day of the 11th of April, 2013, a group of college students got together at 10AM for one epic purpose: taking apart skateboards and rebuilding them with ridiculous specifications for the good of science and mankind.
One group of students rose above all the rest to one of the harshest problems plaguing mankind today...
Does a skateboard rider's weight make a difference on the speed or distance traveled?
This is the question pondered in this particular presentation.Hypothesis!
The overall hypothesis is that weight doesn't have an effect on a rider's velocity or distance traveled.
Not convinced by bold font? Go down.Basically, we have two equations for a change in Kinetic Energy. One based on gravitational potential/acceleration...
and the other based on the velocity of the rider.
Both are based on changes in potential energy.
Putting these two equations together mathematically results in this equation...
(the adjusted for friction version right here)
Wait, where did the mass go?
Mass in the long run cancels out, leaving only h (distance) as the factor that can change things.
Weight should, therefore, not matter.On to the measurements!
...Just kidding. Some details about the measurement process come first. That's important.To make calculations, the initial contact time of the nose of the skateboard and a chalked mark drawn on the ground was recorded as a starting time.
When the skateboard's nose passed another chalked mark, that was recorded as a stopping time.
The time within that interval was calculated, and the amount of white chalk marks the rider passed was counted up.
(Note that measurements that were taken might not have been extremely accurate because it was difficult to pinpoint the exact time at which the rider crossed the markers in the video.)
All of this calculation gives distance traveled and time taken, so each rider's speed was calculated based on this.
distance traveled/time elapsed = speed.
For real this time, here is our data!
Here is our data!
x ||Rider 1, Run 1||Rider 1, Run 2||Rider 2, Run 1||Rider 2, run 2 | #######||##############||##############||##############||###############| Start ||10:04 ||7:20 ||9:29 ||8:07 | time || || || || | #######||##############||##############||##############||###############| End ||11:17 ||8:29 ||12:01 ||9:10 | time || || || || | #######||##############||##############||##############||###############| Distance|20 ft. ||15 ft. ||20 ft. ||10 ft. | #######||##############||##############||##############||###############| Time ||1.4333 ||1.3 ||2.06667 ||1.1 | Elapsed||seconds ||seconds ||seconds ||seconds | #######||##############||##############||##############||###############| Speed ||13.95 ft/s ||12.5 ft/s ||9.68 ft/s ||9.09 ft/s | #######||##############||##############||##############||###############| Avg. ||13.225 ft/s ||9.385 ft/s | Speed || || | #######||##############||##############||##############||###############|
Conclusions!
It means that the initial hypothesis...was wrong.
Weight did affect the speed of the rider!
From the data, it appears that rider 1 (the lighter rider) had a faster average speed than rider 2 (the heavier rider).
Perhaps it was because of how much more energy it actually took to get a heavier rider going on the horizontal ground. If it was a pure downhill drop, the hypothesis could have been correct. However, there was also a horizontal push involved in this case.
Ways the results could have been improved!
It all boils down to taking more accurate measurements!
Using a stopwatch at the scene to measure time passed would have provided for more accurate time measurements, rather than calculating by eye the time elapsed from the video.