This is a related rates problem. You need a general relationship between theta and y. After you get that, you can differentiate it (possibly using implicit differentiation) to get a relationship between dtheta/dt and dy/dt.
A ladder is resting against a vertical wall.The top slides down in the -y direction and the bottom in the -x direction.
What is dtheta/dt (where theta is the angle btw x axis and ladder)when the top of the ladder has -2.6m/s j and the angle btw the x axis and ladder is 26deg.
I have worked out that the i component of vel is 0.634039m/s,but dont know how to calculate dtheta/dt.
Length of ladder is 0.155meters
ans=-18.663 rad/s