AS Daily A Level Physics question
In a lab, a 2.0 N weight stretches one light spring by 8.0 cm. The same weight is then hung from two identical springs arranged in parallel (both attached to the support and to the weight). What is the new extension of the system, and why?
Answer
The correct answer is B.
Correct: B — 4.0 cm, because each spring takes half the force so the pair is twice as stiff. A is wrong because extensions do not add in parallel; both springs have the same extension, and halving the force halves each spring’s extension (8.0 cm → 4.0 cm), not to a quarter. B is correct since two identical springs in parallel double the effective stiffness, so the extension halves. C is wrong because it ignores the increased stiffness of the parallel pair. D is wrong because it confuses parallel with series; two identical springs in series would double the extension, not parallel.