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A tennis ball is thrown up and reaches a heightof 4.05 m before coming down. What was itsinitial velocity? How much total time will ittake to come down? Assume g = 10 m/s^2 |
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Answer» Displacement (s) = 4.05 m g = -10 m/s² Final velocity (v) = 0 m/s To find: Initial velocity (u) = ? ttotal (t) = ? Formulae: v² = u² + 2gs, u + gt ttotal = 2 × t Solution: v² = u² + 2gs 0² = u² + 2 × (-10) × 4.05 0 = u² - 81 u² = 81 u = 9 m/s v = u + gt 0 = 9 + (-10) × t 10 t = 9 t = 0.9 s Time of ascent = Time of descent ttotal = 2t = 2 × 0.9 = 1.8 s The initial velocity was 9 m/s and total time taken to come down, is 1.8 s. |
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