Answer
The two balls pass each other at a height of **20.4 meters** above the ground after **2 seconds**.
Work Step by Step
\[ V_{ia} = 5 \, \text{m/s} \]
\[ X_{ia} = 30 \, \text{m} \]
\[ V_{ib} = 20 \, \text{m/s} \]
\[ X_{ib} = 0 \, \text{m} \]
\[ X(t) - X_i = V_{i}t - \frac{1}{2}gt^2 \quad (\text{Equation of motion}) \]
\[ X_A(t) - 30 = 5t - \frac{9.8}{2}t^2 \]
\[ X_B(t) - 0 = 20t - \frac{9.8}{2}t^2 \]
Setting \( h_A(t) = h_B(t) \) to Find the Time They Pass:
\[ 30 + 5t - 4.9t^2 = 20t - 4.9t^2 \]
\[ 30 = 15t \]
\[ t = 2 \, \text{seconds} \]
\[ X_B(2) = 20.4 \, \text{meter} \]
