Answer
(a) A = 10 cm
(b) f = 0.5 Hz
Work Step by Step
(a) The motion moves between -10 cm and 10 cm. Therefore, the amplitude is 10 cm.
(b) From the graph, we can see that two cycles are completed in 4 seconds. Therefore, the period $T = 2~s$. This means that the frequency is:
$f = \frac{1}{T} = \frac{1}{2~s} = 0.5~Hz$