Two bodies were thrown simultaneously from the same point, one straight up and the other at an angle θ = 60° to the horizontal. The initial velocity of each body is u = 30 m/s. Neglecting air resistance, find the distance between the bodies after 2 seconds.
For the first body, the distance moved in the vertical upward direction in time t is:
y = ut − 1/2gt²
For the second body, the horizontal distance is:
x' = u cosθ · t
and the vertical distance is:
y' = u sinθ · t − 1/2gt²
Vertical distance between two bodies after time t:
y − y' = u sinθ · t − ut
Distance between two bodies after time t:
= √[(x')² + (y − y')²]
= √[(u cosθ · t)² + (u sinθ · t − ut)²]
= ut √[(cos²θ + sin²θ) + 1 − 2 sinθ]
= ut √[2(1 − sinθ)]
Substituting u = 30 m/s, t = 2 s, θ = 60°:
= 30 × √2(1 − sin 60°) = 30 m