(d) $v_{1} = \frac{dy_{1}}{dt} = 2 \times 10\cos{(10t + \theta)}$; $v_{2} = - 3 \times 10\sin{10t = 30\cos{(10 + \pi/2})}$ $\therefore$ Phase difference$= (10t + \theta) - (10t + \pi/2)$
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.