A body falls from rest through a height of 1 km under gravitational acceleration of 10 m/s2 and is then brought to rest by penetrating a depth of 200 m into sand. The average deceleration of the body during its penetration into the sand is:

A particle moves along a plane curve with a uniform speed v. Its angular velocity about a fixed point O in the plane, when it is at a point P of its path, is:

If the horizontal range of a projectile is four times its maximum height, then the angle of projection is: