# Projectile Motion

1. Sep 20, 2009

### linds1369

1. For women's volleyball the top of the net is 2.24m above the floor and the endline is 9.00m from the net. Using a jump serve, a player strikes the ball at a point 3.00 m above the floor and 8.00m (horizontally) from the net. If the initial velocity of the ball is horizontal and directed perpendicular to the endline, (a) calculate the minimum initial speed the ball must have to clear the net. (b) calculate the maximum initial speed the ball can have to stay inside the court.

2. Sep 20, 2009

### RoyalCat

What equations do you think are relevant? How do you think you should approach the problem?

3. Sep 20, 2009

### linds1369

Well, initially I thought to find theta and solve for V0x=V0cos(theta) but I have no initial velocity. I'm stuck trying to find an equation that I don't need time or velocity for. I just can't quite figure out where to start.

4. Sep 20, 2009

### RoyalCat

Try and synthesize an equation describing the trajectory of the projectile.

$$x(t)=\tfrac{1}{2}a_x t^2+v_{0_x}t+x_0$$

$$y(t)=\tfrac{1}{2}a_y t^2+v_{0_y}t+y_0$$

Try and build the function $$y(x)$$ by isolating $$t(x)$$ and then plugging it into the $$y(t)$$ equation.
It should be smooth sailing from there on, just a question of plugging in the x and y values for each situation.