√5π
2π√3
√52π
4π√5
Amplitude, A = 3cm
In Harmonic Motion, x = A sinωt, where ω = 2π/T
v = Aω cosωt
Acceleration, a = -Aω² sinωt
At x = 2cm
|v| = |a|
|Aω cosωt| = |-Aω² sinωt|
Asinωt = 2cm
3sinωt = 2
sinωt = 2/3
cosωt = √1 - (2/3)² = √5/3
From eqn. (1)
|3ω√5/3| = | -ω² x 2/3 |
ω = √5/2
2π/T = √5/2
T = 4π/√5