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:
Explained
Explanation:
Newton would resort to the classical mechanics and say that the momentum of the particle that is moving with a constant velocity will be given by: momentum = mass x velocity
this approach will highlight the particle nature and will not be relativistic.
De-Broglie will say that the momentum of the particle is related to its associated matter wave and the relation between them is given by:

where \lambda = wavelength of the matter wave associated to the particle, h = planck's constant
and
thus, this highlights the wave nature of the particle and is also relativistic.
Draw a circuit that contains 2 batteries, three lights in parallel and a switch that controls the whole circuit.
Answer:
x = 2000 Km
Explanation:
Given
y = 10 km
Slope: 1 : 200
x = ?
We can apply the formula
y / x = 1 / 200 ⇒ x = 200*y = 200*10 Km
⇒ x = 2000 Km
Answer: Most inhabitants of urban areas have nonagricultural jobs meaning not of, relating to, or used in farming and agriculture nonagricultural products/land. Urban areas are very developed, meaning there is a density of human structures such as houses, commercial buildings, roads, bridges, and railways.
Explanation:
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