December 14 ,2010 - Starting to Going Over Lesson 8

Today in class we started by finishing watching Mythbusters.
After we finished watching the video, we went over lesson 8.
8.1 a) We said that the Americans With Disabilities Act is concerned with the steepness of accessibility ramps because there shouldn't be too much force (not work) needed to go up the ramps. It isn't about work because the amount of work stays the same no matter how steep the ramp is. This is because when the ramp becomes less steep, there is less force but the distance increases.
b) since the ratio for the height and width of the ramp was 1:12, I said that possible ramps are 3m by 36m, 5m by 60m, and 12m by 114m.
c)I said that ramp "iii" fits the requirement.
In class we learned that you can find how much force needs to be applied to something by doing (Mass * 10). This is only true with kilograms so if it is in any other units, it must be converted into kilograms.
d)
i) To find out how much work is done on that ramp, we needed to know that Force * Displacement = Work. Using this rule, Mass * 10 = Force, we found out that we would need to apply 200N. The height of the ramp was 2meters so the displacement is 2m. By doing 200N * 2, we found out that it would take us 400J of work to push a wheelchair up the ramp.
Class ended so we did not go over the rest of problem d)

I was still confused about why we take the height of the ramp for displacement and not how much you traveled/moved the wheelchair

-AT