A projectile is projected at 60° above the horizontal. At the instant its velocity becomes perpendicular to its initial velocity, which statement is correct?
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A projectile is projected at 60° above the horizontal. At the instant its velocity becomes perpendicular to its initial velocity, which statement is correct?

G1 Physics · Accepted Answer

For perpendicularity, t = u/(g sinθ). The time of flight is T = 2u sinθ/g. Hence t/T = 1/(2sin²θ). For θ=60°, sin²60°=3/4, so t/T = 2/3. Horizontal speed is constant, therefore x/R = t/T = 2/3. Thus t=2T/3 and x=2R/3.