1. The problem statement, all variables and given/known data A particle moves with const speed v along the curve r(θ) = a(1+cos θ). Starting with the general expression for the velocity vector v in polar coordinates solve for θ_dot in terms of v, k, and θ. What does the sign of θ_dot signify? 2. Relevant equations v = r_dot*r_hat + r*θ_dot*θ_hat v = v * v_hat r(θ) = a(1+cos θ) r_hat = x_hat cos Θ + y_hat sin θ v 3. The attempt at a solution r_dot = -a sin θ solving for θ_dot: θ_dot = (v - r_dot * r_hat)/(r*Θ_hat) I am lost here, I think I am missing some important relation and something that comes out of the fact that the speed in constant but I don't know what. Any help would be greatly appreciated thanks. Edit: I think I've got it, since the magnitude of unit vectors are one and θ_dot is a scalar I can just stop at θ_dot = (v - r_dot * r_hat)/(r*Θ_hat) = (v*v_hat - r_dot * r_hat)/(r*Θ_hat) = (v-r_dot)/r = (v+a sin θ)/(a + a cos θ) Is this right? What does the sign mean then, just the value?