Question

An Earth's satellite is moving in a circular orbit with a uniform speed $v$. If the gravitational force of the Earth suddenly disappears, the satellite will

• A. vanish into outer space.
• B. continue to move with velocity $v$ in original orbit.
• C. fall down with increasing velocity.
• D. fly off tangentially from the orbit with velocity $v$.

Answer 1

Answer: (D)

fly off tangentially from the orbit with velocity $v$.

The satellite revolves around the Earth in a circular orbit when centrifugal force acting outward on the satellite is balanced by the gravitational force of the Earth. Thus, when gravitational force suddenly disappears, then only centrifugal force will be acting and velocity is tangential to the orbit and hence, the satellite will fly off tangentially. It is similar to an object tied with a string, fly off when string suddenly breaks.