14.24 A body describes simple harmonic motion with an amplitude of 5 cm and a period of 0.2 s. Find the acceleration and velocity of the body when the displacement is
(a) 5 cm                (b) 3 cm                (c) 0 cm..

It is given in the questions that:

Amplitude, A=5 cm=0.05 m
 Time period, T = 0.2 s
 For displacement, x = 5 cm = 0.05 m
 Acceleration:
a=-ω2x
=-2πT2x
=-2π0.22×0.05
=-5π2 m/s2
Velocity: 
v=ωA2-x2
=2πT0.052-0.052
=0
For displacement, x = 3 cm = 0.03 m
Acceleration: 
a =-ω2x
=-2πT2x
=-2π0.22=0.03
=-3π2 m/s2
Velocity: 
v=ωA2x2=2πTA2x2=2πT(0.05)2(0.03)2=2π0.2×0.04=0.4π m/s
For displacement, x = 0 
Acceleration:
 a=-ω2x=0
 Velocity:
v=ωA2x2=2πTA2x2=2π0.2(0.05)20=0.5π m/s