4. A uniform rod 9 m long weighing 40 kg is pivoted at a point 2 m from one end where a weight of 120 kg is suspended. The required force acting at the end in a direction perpendicular to rod to keep it equilibrium, at an inclination 60° with horizontal, is
8. For interpolation of satellite data used for monitoring dynamic changes that occure on the earth surface, the most suitable orbit for the satellite is :
