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This is my first visit to this website. I am a 43-year-old undergraduate majoring in Environmental Horticulture and somehow missed physics along the way. It's been 2-3 years since I had all my algebra, trig and pre-calc and now in my first 2 weeks of physics I find I need help. We just studied projectile motion and the problems that go with it. I think I understand the concepts and can find the answer to a problem that deals with how far the projectile travels given an inital velocity and angle. However, the problem I'm trying to do now the distance is given and I need to come up with the time and the velocity. I actually have my instructor's notes how to solve this, but his notes seem more convoluted than what it necessary based on other websites I have seen. Also, I notice that everyone uses different formulas or at least different symbols in those formulas and it is all very confusing. At any rate, the problem is A daredevil jumps a canyon 15 m wide by driving a motorcycle up an incline sloped at an angle of 37 degrees with the horizontal. What minimum speed must she have in order to clear the canyon? How long will she be in the air? He starts out with the horizontal being Vo = 15/.8t and I'm ok with that until later. Then for the vertical, working from the equation y = Voyt - 1/2 a(or g in this case)t^2, my professor works to Vo sin 37 deg. t - 5t^2 = 0. Here's where I get confused. Does the 5 in the 5t^2 come from 1/2 of 10 m/s for g and how does this equation equal 0 and what is the significance of that? He then goes on to substitutions and other things that I pretty much understand, but I can't get past this zero business.

Thanks for your help and this probably won't be my last post this semester!

Amy

Gainesville, Florida

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# Homework Help: Projectile Motion

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