1. The problem statement, all variables and given/known data Prove that if v(t) is any vector that depends on time, then v'(t) is orthogonal to v(t). Hint given: Consider the derivative of v^2. 3. The attempt at a solution V'^2 = d/dt (v * v) = v d/dt + v d/dt = d/dt (v+v) = 2v d/dt ??