how can i set up this problem?

Problem 3 (25 pts) Screen w (t) ts v(t) ts =t+ (a) (10 pts) As shown in the figure above, suppose at time t a particle of charge q is at position w(t) with velocity v(t). The particle radiates out energy dW towards a small solid angle along the direction of r, as shown in the figure above, and at a rate of dWparticle/ dt. At some time to later, that energy arrives at a screen that is far away from the particle and the rate which the screen receives that energy is dW screen / dts. Show that dW particle n . u dW screen dt (8) cr at s where u = ci - v(t)