AS Daily A Level Physics question
On level ground, a tennis ball launcher fires balls at 45° to the horizontal. Ignoring air resistance, the coach doubles the launch speed but keeps the angle the same. What happens to the horizontal range?
Answer
The correct answer is D.
Correct: D — The range becomes four times larger. For a fixed launch angle on level ground, range is proportional to the square of launch speed, so doubling speed makes the range 2^2 = 4 times larger. A The angle being unchanged does not fix the range; range increases with speed squared. B Doubling speed does not just double the range because range is not linear in speed. C Three times larger is a common guess but incorrect; the square dependence gives a factor of four, not three. D Correct because range ∝ (launch speed)^2 at fixed angle, giving a fourfold increase.