Assume the motion is described by x(a, t)- aet (a) consider the cross-section that at = 5 is located at x = 1 , where was it at t 0? (b) find u(r, t) and u(a, t) (c) find v(x, t) and v(a, t) (d) what is the velocity of the cross-section that is at x 2 at time t? what is the velocity at time t of the cross-section that starts at x -2? e) suppose the temperature of the bar is 0(x, t) -r5 + 4t. what is the rate of change of î¸ following a material section?