7. A particle with mass m and positive charge q starts from rest at the origin of the coordinate system shown in the gure below. A uniform electric field with the direction shown in the gure exists together with a uniform magnetic in the region of space in which the particle is moving. (a) Explain why the particle will move under the action of these two elds as indicated in the figure. You must show a detailed set of sketches of the acting forces, and the velocity components of the particle at relevant points in the trajectory, as this part involves understanding the motion along the x- and y-direction separately. (b) Show that the speed at any point is given by the following expression, x/Zqu / m . (c) It can be shown that the radius of curvature at the top points is twice the y-coordinate at that level. Work out an expression for the speed at the top point of the trajectory depending only on the two fields, E and B