Wile E. Coyote Lands in the RiverDate: 08/20/99 at 17:28:42 From: Saddie Subject: Velocity Dr. Math: I've tried to figure this problem out, but I've never been good at these velocity equations. Here's the problem: "Wile E. Coyote is standing on a springboard atop a high cliff. Roadrunner drops a boulder on the other end of the springboard, sending Wile up with an initial velocity of 4 meters/sec. At what time will he land in the river, 120 m below the top cliff?" They give me the hint of using the equation h = -16t^2 + (v_o)t + s. What do I put in for the o and the s? I understand that that I am solving for t. Please help! Thanks! Date: 08/20/99 at 20:02:58 From: Doctor Ian Subject: Re: Velocity Hi Saddie, What this equation is saying, in English, is Your height at Your original your upward your downward some moment, t = height + motion if - motion due to there were no gravity gravity 1 h = s + v t - - gt^2 o 2 So 's' is Wile E.'s original height: 120 m above the river. And 'v_o' is his 'original velocity' (or his 'velocity at time t = 0', depending on whether you want to read the subscript as an 'o' or a '0'): 4 m/s. Can you take it from here? Be careful - the formula assumes that the value of g (the acceleration due to gravity) is 32 ft/sec^2 (half of which is 16 ft/sec^2), but the problem gives you everything in meters. The metric value of g is 9.8 m/sec^2. Also, it's obviously a trick question - he won't land in the river at all. He'll hit the ground next to the river! - Doctor Ian, The Math Forum http://mathforum.org/dr.math/ |
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