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Apex Clear
A tennis player standing 14.1 m from the net hits the ball at 3.10° above the horizontal……?
full question: A tennis player standing 14.1 m from the net hits the ball at 3.10° above the horizontal. To clear the net, the ball must rise at least 0.251 m. If the ball just clears the net at the apex of its trajectory, how fast was the ball moving when it left the racquet?
very confused on what equation to use?
You actually have simultaneous equations here.
What you really need to do is to calculate the height at the net in terms of the speed coming off the racquet. It’s easy to calculate x(t) and y(t), but you need to calculate when x(t) = 14.1 m (let’s call this Tnet) and then see if y(Tnet) is 0.251 m or greater.
Both of these equations will be functions of the speed, s. Once you have that, you’re done.
I get
x(t) = s cos 3.1° t
y(t) = -4.9 t² + s sin 3.1° t + 0
Tnet = 14.1 / ( s cos 3.1° )
