An army vehicle (tank) is going along a curve of radius 100m at 20m/s while its speed is decreasing at 1m/s each sec. The tank has a turret which has angular velocity of 3rad/s CW but the angular velocity is decreasing at 0.2rad/s each sec at this instant. A shell in a gun attached to the turret has a velocity of 200m/s and decreasing speed at 1m/s each sec. Determine the acceleration of the shell with respect to ground at this instant. State all assumptions. You need to choose orientation of fixed and moving reference frames. You can choose in such a way that this simplifies your calculation.