Answer:
Cosmic ray's frame of reference: 99,875 years
Stationary frame of reference: 501,891 years
Explanation:
First of all, we convert the distance from parsec into metres:

The speed of the cosmic ray is

where
is the speed of light. Substituting,

And so, the time taken to complete the journey in the cosmic's ray frame of reference (called proper time) is:

Converting into years,

Instead, the time elapsed in the stationary frame of reference is given by Lorentz transformation:

And substituting v = 0.98c, we find:

Answer:
a)
, b) 
Explanation:
a) The minimum coeffcient of friction is computed by the following expression derived from the Principle of Energy Conservation:




b) The speed of the block is determined by using the Principle of Energy Conservation:




The radius of the circular loop is:



Explanation:
The distance traveled north ward = 2 miles
distance traveled south ward = 3miles
Displacement is the distance traveled in a specific direction. So, it depend on the start and finish point.
The displacement = 3 miles - 2miles = 1mile southward
Distance is the total length of path;
Distance = 3 miles + 2 miles = 5miles