Question

A ball is projected horizontally with a velocity of 30m/s from the top of a high tower. Air resistance may be neglected. After what time will it's velocity be in the direction 45 degrees to the horizontal?

Answer 1

Its velocity will point down 45 degrees when its vertical speed has grown to 30 m/s to match its horizontal speed.

Gravity is increasing the downward speed of the ball by 9.8m/s every second.

So its downward speed will be 30 m/s after (30) / (9.8) = 3.06 seconds