A2 Daily A Level Physics question
In a lab, a spring launcher fires a steel ball at a fixed speed and fixed angle above the horizontal relative to the launcher. First, the launcher is clamped to the bench; then it is mounted on a trolley that moves horizontally at constant speed during the launch. The ball lands at the same height as it is launched in both trials, and air resistance is negligible. Which statement must be true when comparing the trolley launch with the clamped launch?
Answer
The correct answer is A.
Correct: A — Maximum height and time of flight are unchanged; horizontal range increases. A is correct because the added trolley speed is horizontal only, so the vertical component (and therefore peak height and time) is unchanged while the greater horizontal speed increases range. B is wrong because extra horizontal speed does not add to the vertical component, so height does not increase and the range would not stay the same. C is wrong because the time of flight depends on the vertical motion, which is unchanged; additionally, the greater horizontal speed means the range cannot be unchanged. D is wrong because the vertical component set by the launcher is unchanged, so neither maximum height nor time of flight increases, even though the range does.