Two simple harmonic motions are represented by the equations y1=0.1sin(100πt+π/3) and y2=0.1cosπt. The phase difference of the velocity of particle 1 with respect to the velocity of particle 2 is at t=0

On differentiating the equations given, we know that there will be the phase change in respective equations of v1 and v2. Now in the first equation, the phase is -π/2 + π/3 = -π/6 and in the other case, the phase will be 0, therefore the phase difference is -π/6, which is nothing but option B. Phase difference (Φ) = 99πt + π/3 - π/2. At t=0; Φ = -π/6