In order to escape the gravitational pull of our planet, any object must have an escape velocity of 7 km/s or more, anything lower than that will be slowed down by the pull of gravity, and will eventually returned to the surface of our planet. It is independent of mass, any lighter or heavier object must attain the required escaped velocity to reach space.
The right answer is
all of the above
good luck
The international system of units is the designated system of units used by scientist in every part of the world to keep data in the same form and measurements, this is to avoid confusion and the need to convert data when being shared. typically described in meters or kilometer over a time form usually seconds or hours.
To develop this problem it is necessary to apply the concepts related to Gravitational Potential Energy.
Gravitational potential energy can be defined as

As M=m, then

Where,
m = Mass
G =Gravitational Universal Constant
R = Distance /Radius
PART A) As half its initial value is u'=2u, then



Therefore replacing we have that,

Re-arrange to find v,



Therefore the velocity when the separation has decreased to one-half its initial value is 816m/s
PART B) With a final separation distance of 2r, we have that

Therefore




Therefore the velocity when they are about to collide is 