A ball is thrown vertically upward with initial speed 150 m s⁻¹. The ratio of its velocities after 3 s and 5 s is (x+1)/x. Find x. Take g = 10 m s⁻².
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Question

A ball is thrown vertically upward with initial speed 150 m s⁻¹. The ratio of its velocities after 3 s and 5 s is (x+1)/x. Find x. Take g = 10 m s⁻².

G1 Physics · Accepted Answer

Velocity after time t: v = u - gt At t = 3 s: v₃ = 150 - 30 = 120 m s⁻¹ At t = 5 s: v₅ = 150 - 50 = 100 m s⁻¹ Thus, v₃/v₅ = 120/100 = 6/5 Given: (x+1)/x = 6/5 5x + 5 = 6x x = 5 Hence option B follows.