## anonymous 5 years ago A golf ball is hit from the ground with an initial velocity of 208 feet per second. Assume the starting height of the ball is 0 feet. How long will it take the golf ball to hit the ground 13 secs 21 secs 42 secs 6 secs

1. anonymous

It depends on the velocity (you've just given speed, which is the magnitude of velocity), but, given the initial conditions, the equation of motion in the vertical would be$y=-16t^2+208 \sin \theta t$(which I can explain if you need). The maximal time of flight is had when the height of the ball is 0 (i.e. at the end). So we have from the quadratic:$0=-16t^2+208 \sin \theta t \rightarrow t^2(t-13 \sin \theta ) =0$which means either$t=0$(i.e. beginning, which we're not interested in) or,$t=13 \sin \theta$The maximum value sine can take is 1, so the maximum time you can have is t=13, BUT you may also have t=6 for an angle of approx. 27.5 degrees. You need the initial direction of the ball.

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