A spherical non-rotating planet (with no atmosphere) has mass 4 kg and radius 9000 km. A projectile of mass is fired from the surface of the planet at a point with a speed at an angle with respect to the radial direction. In its subsequent trajectory the projectile reaches a maximum altitude at point on the sketch. The distance from the center of the planet to the point is . Use .

Question

A spherical non-rotating planet (with no atmosphere) has mass    4   kg and radius    9000  km. A projectile of mass       is fired from the surface of the planet at a point   with a speed     at an angle     with respect to the radial direction. In its subsequent trajectory the projectile reaches a maximum altitude at point   on the sketch. The distance from the center of the planet to the point   is      . Use          .

What is the initial speed     of the projectile? (in m/s)