AS Daily A Level Physics question
A student throws a tennis ball straight up from hand level with speed u. In a second trial, they throw it straight up from the same height with speed 2u. Ignore air resistance. Compared with the first throw, what happens to the total time from release until the ball returns to hand level in the second throw?
Answer
The correct answer is B.
Correct: B — It doubles. With constant g and no air resistance, the time to rise is proportional to the initial upward speed, and the full up-and-down time is twice that, so doubling the launch speed doubles the total time. A is wrong because a greater initial speed means it takes longer to slow to zero on the way up (and the descent time matches the ascent), so the total time cannot stay the same. B is correct because time of flight for vertical throw scales linearly with initial speed when acceleration is constant. C is wrong because the √ relation applies to how height depends on time or speed (height ∝ speed²), not to the time of flight; time does not scale as √(speed). D is wrong because quadrupling confuses the squared dependence of maximum height with the linear dependence of time on initial speed.