You shoot a projectile at an unknown angle but at a velocity of 15m/s. You know that this must hit a target 20 feet away (height of the target negligible). What is the time of the flight and how do you get it.
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Expert's answer
2011-10-11T12:32:35-0400
Let Alpha be the angle between the direction of the shoot and the horizont, V=15m/s is the initial velocity. Let T be the time while the projectile flies. Then S = V*cos(Alpha)*T - equation along the horizontal axis (S = 20 feet). V*sin(Alpha) = g*T/2. From the first equation (cos(Alpha))^2 = (S/(V*T))^2, from the second (sin(Alpha))^2 = (g*T/(2V))^2. As (sin(Alpha))^2+(cos(Alpha))^2 = 1, then:
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