A body is projected with velocity u at angle θ to horizontal. The horizontal range is maximum when θ is:
A. 30°
B. 90°
C. 60°
D. 45°
Answer: Option D
Solution (By JKSSB Mock Tests)
Horizontal range R = u²sin(2θ)/g. sin(2θ) is maximum (value 1) when 2θ = 90° ⇒ θ = 45°. Thus maximum range at 45° projection angle, assuming same initial speed and level ground. Memory tip: 'Max range at 45°; max height at 90°'. This standard projectile motion result is frequently tested in competitive exams. Always verify assumptions: no air resistance, uniform gravity, launch and landing at same height. For different heights, optimal angle differs.
Explanation:
Acceleration phase: s₁ = ½a t² = ½×2×100 = 100 m, v = a t = 20 m/s. Constant velocity phase: s₂ = v×t = 20×10 = 200 m. Total = 300 m. Motion in two parts.
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