In a Physics lesson, Chantelle adds weights to a spring and carefully measures the extension. She finds that the weight,
y g is related to the extension, x cm by the formula
y = 0.5x + 1 for 0 ≤ x ≤ 20.
a Draw the graph of y against x for 0 ≤ x ≤ 20.
b Use this graph to find the
(i) weight for a 17 cm extension
(ii) extension produced by a 5 g weight.
c What would Chantelle’s formula predict for the spring’s
extension for a 1 kg weight? Comment on your answer.