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# Projectiles! watch

1. A tennis ball is served so that it initially moves horizontally at a speed of v m/s from a point 3m above the baseline, A. Point A is 12m away from the net, which is 1m high, at point B. The distance from point B to point C, which is the centre of the oppoiste court, is 6m. The ball must pass over the net, and must land on the other side of the court between points B and C. Assume that there are no resistance forces and the ball moves in a vertical plane at right angles to the net. If g = 10 m/s^2 :

a.i. Show that v must be greater than sqrt(360) m/s if the ball is to get over the net.

a.ii. What is the mximum value of v if the ball is to land in the area between B and C?

Where do I even start?
2. For part i you need to consider how long it would take the ball to drop from 3m to the height of the net at 1m. The ball must go horizontally at least 12m (distance from A to the net) in this time to clear the net. You will need to consider the horizontal and vertical velocities and accelerations separately.

Apply a similar principle to part ii.
3. How do you work out the vertical velocity when you are only told that the horizontal verlocity is v though?
4. got it, cheers

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Updated: March 30, 2011
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