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twotaileddemon
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Homework Statement
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
Homework 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*
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 ^_^