Complementary launch angles
Two identical projectiles are launched from level ground at the same speed, one at 30° and one at 60° above horizontal. Ignoring air resistance, how do their horizontal ranges compare?
Answer D: explanation for every choice
A
The 60° projectile stays in the air longer but moves more slowly horizontally, which exactly offsets.
B
The 30° projectile moves faster horizontally but lands sooner, which exactly offsets.
C
Without air resistance, mass doesn't affect projectile motion.
D
Correct. Range = v² sin(2θ)/g, and sin 60° = sin 120°, so complementary angles give the same range.
TakeawayRange ∝ sin 2θ. Complementary angles give equal ranges, and 45° gives the maximum.
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Reviewed 2026-11-05 by a medical student. Spot an error? Report it with question ID cp110.