Answer:
The shortest distance is
Explanation:
The free body diagram of this question is shown on the first uploaded image
From the question we are told that
The speed of the bicycle is 
The distance between the axial is 
The mass center of the cyclist and the bicycle is
behind the front axle
The mass center of the cyclist and the bicycle is
above the ground
For the bicycle not to be thrown over the
Momentum about the back wheel must be zero so

=> 
=> 
Here 
So 
Apply the equation of motion to this motion we have

Where 
and
since the bicycle is coming to a stop

=>
When you refer to how close a measured value is to a standard, accepted or known value, you are talking about the ACCURACY of the data. This is the definition of accuracy when it comes to engineering and other fields of science.
Accuracy is usually associated or with the term precision, as their definitions are often interchanged.
The answer you have is right good job 12
Luster I think is what you are looking for
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 