A particle is projected with 20 m/s at an angle 60° with the horizontal. At what time it is moving at an angle 45° with the horizontal while moving downwards?

Question

G1 Physics · Accepted Answer

uₓ = 20 cos60° = 10 m/s, uᵧ = 20 sin60° = 10√3 m/s. While moving downward at 45°, (uᵧ-gt)/uₓ = -1, so t = √3+1 ≈ 2.732 s.