Physics · MOTION IN A STRAIGHT LINE

A ball is thrown vertically upwards from the top of a building of height \( 25 \text{ m} \) with an initial speed of \( 20 \text{ m/s} \). At the exact same instant, a second ball is dropped from rest from a point \( 45 \text{ m} \) directly above the ground. Taking \( g = 10 \text{ m/s}^2 \), find the time elapsed before the two balls cross each other in air.

1. A
   \( 0.5 \text{ s} \)
2. B
   \( 2.0 \text{ s} \)
3. C
   \( 1.5 \text{ s} \)
4. D
   \( 1.0 \text{ s} \)