The angle between the initial and final velocities of a ground-to-ground projectile is 120°. The angle of projection is:
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The angle between the initial and final velocities of a ground-to-ground projectile is 120°. The angle of projection is:

G1 Physics · Accepted Answer

Initial velocity makes angle +θ with the horizontal. Just before landing at the same level, the velocity makes angle −θ with the horizontal. Therefore the angle between the two velocity vectors is 2θ. Given 2θ=120°, so θ=60°.