Amplitude = 5 cm = 0.05 m

Time period = 0.2 s

When the displacement is y, then

acceleration, A = -ω^{2}y

Velocity, v =\( \omega \sqrt{r^{2}-y^{2}}\)

ω = \( \dfrac{2π}{T}\)

= \( \dfrac{2π}{0.2}\)= 10π rad/s

**(a)** When the displacement y = 5 cm = 0.05 m

Acceleration, A = – (10π)^{2}(0.05)

= 5π^{2} m/s^{2}

Velocity, V = \( 10\pi \sqrt{(0.05)^{2}-(0.05)^{2}}=0\)

**(b)** When the displacement y = 3 cm = 0.03 m

Acceleration, A = – (10π)^{2}(0.03)

= 3π^{2} m/s^{2}

Velocity, V = \( 10\pi \sqrt{(0.05)^{2}-(0.03)^{2}}\)

\( =10\pi \times 0.04 = 0.4\pi m/s\)

**(c)** When the displacement y = 0

Acceleration, A = – (10π)^{2}(0) = 0

Velocity, V = \( 10\pi \sqrt{(0.05)^{2}-(0)^{2}}\)

\( =10\pi \times 0.05 = 0.5\pi m/s\)

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