(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A soccer player kicks a rock horizontally off a 40 m high cliff into a pool of water. If the player hears the sound of the splash 3 seconds later, what was the intial speed given to the rock? Assume that the speed of sound in air is 343 m/s

2. Relevant equations

V_f = V_i - gt

X_f = x_i + vt - 1/2gt^2 (which becomes zero)

Y_f = Y_i + vt (which becomes zero) -1/2gt^2

y direction velocity = v_i sin*

x directino velocity = v_i cos*

3. The attempt at a solution

Well first I tried using -1/2gt^2 to find the y_f, just to check its validity... and I got y_f = -44.1 m, which is lower than the cliff...

And I also found t = 2.857 to get to y_f = -40

But I'm so confused with so little data. I know that:

y_i = 0 m

y_f = -40 m or -44.1 m

t = 3s

x_i = 0m

x_f = ?

a_x = 0 m/s^2

a_y = -9.8 m/s^2

v_x = ? m/s

v_y = 0 m/s

Could someone possibly guide me a little bit, since I'm not understanding the equations properly, I guess. Thanks ^_^

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# Homework Help: Projectile Motion of soccer ball

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