Question

A body is projected at an angle of 30° with a velocity 30 mm/s.Find the angle with horizontal after 1.5sec.

Answer 1

Let the velocity be 30 m/s, but not 30 mm/s

Along vertical velocity after time t is given by
vSinφ = uSinθ - gt
vSinφ = 30Sin30 - (10 × 1.5)
vSinφ = 15 - 15
vSinφ = 0
Sinφ = 0°

Angle with horizontal after 1.5 seconds is 0°. It means body is at maximum height height.