Answer
The answer to part (b) does not depend on the mass of the ball.
Work Step by Step
We can use conservation of energy to find an expression for the speed when it is 3.0 meters below the window:
$K_f+U_f = K_0+U_0$
$K_f = K_0+U_0-U_f$
$\frac{1}{2}mv_f^2 = \frac{1}{2}mv_0^2+mg(h_0-h_f)$
$v_f^2 = v_0^2+2g(h_0-h_f)$
$v_f = \sqrt{v_0^2+2g(h_0-h_f)}$
We can see that the final speed depends on the initial speed, the acceleration due to gravity, and the difference in initial height and final height.
The answer to part (b) does not depend on the mass of the ball.
