A2 Daily A Level Physics question
In a lab, a 1.0 kg mass is hung from a single light spring and its extension and the elastic energy stored are recorded. The setup is then replaced by two identical springs arranged in parallel that together support the same mass. Neglect the mass of the springs and assume they behave linearly. Compared with the single-spring setup, which statement must be true?
Answer
The correct answer is C.
Correct: C — The extension halves and the total elastic energy halves. A is wrong because sharing the weight means each spring has half the force and half the extension, so each stores a quarter of the energy and the pair store half, not the same. B is wrong because adding a parallel spring shares the load, reducing the total energy stored rather than increasing it. C is correct because halving both force and extension per spring makes each store a quarter of the single-spring energy, and two springs together give half. D is wrong because with two identical springs in parallel the effective stiffness doubles, so the extension halves (not quarters), and the energy does not drop to a quarter.