Answer:
The acceleration that the jet liner that must have is 2.241 meters per square second.
Explanation:
Let suppose that the jet liner accelerates uniformly. From statement we know the initial (
) and final speeds (
), measured in meters per second, of the aircraft and likewise the runway length (
), measured in meters. The following kinematic equation is used to calculate the minimum acceleration needed (
), measured in meters per square second:

If we know that
,
and
, then the acceleration that the jet must have is:


The acceleration that the jet liner that must have is 2.241 meters per square second.
I believe Isaac Newtons Law " Gravity ".
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 
Answer:
1.84 hours or 110.4 minutes
Explanation:
8 miles 1.61 km 1 hr
------------ x ----------------- x -------------- = 1.84 hours or 110.4 minutes
1 mile 7 km