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Practice question

MCQ

Question

A ball is thrown upwards at 45m/s from a 30m tower. What is the time taken to reach a point 15m above the ground? (Take g\=10m/s2)

Options

Choose one · Correct answer highlighted

Explanation

Displacement y=−15m, −15=45t−5t2⇒5t2−45t−15=0⇒t2−9t−3=0. As per NCERT Chapter 3, equations v=u+at, s=ut+½at², v²=u²+2as describe uniformly accelerated motion. Applying correct signs and units gives 9 s as the result, so option A is correct.

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