1. 
If the distance between two masses is increased by a factor of 3, the gravitational force of attraction between them will 




2. 
Two planets of radii R_{1} and R_{2} have the same density. The ratio of their accelerations due to gravity at the surface is 




3. 
A reference frame attached to the Earth 




4. 
If the radius of the Earth were increased by a factor of 2 and its mass remained the same, then the acceleration due to gravity on the Earth would 




5. 
An Earth satellite of mass m revolves at a height h from the surface of the Earth. If R is the Earth's radius and g is the acceleration due to gravity at the surface of the Earth, then the velocity of the satellite is given by 



