Answer:
-62.45m/s and +62.45m/s
Explanation:
The formula for relativistic speed
This is the speed of A with respect to B
where
will be the velocity of person 1: 39m/s
will be the velocity of person 2: -31m/s (negative because is travelling in opposite direction)
and the velocity of light: 100m/s
The velocity of person 1 measured by person 2 is:
The velocity of person 2 measured by person 1 is:
For the part a) we need only the momentum of the box and we have the data to find it.
Momentum is given by,
where clearly, p is the momentum, m the mass of the box and v is the velocity.
Substituting,
For part b) we need an analysis of the situation. We understand that the box on a surface that has no friction will continue to rotate at the same speed previously defined. The box can only stop with friction, so,
<em>It is the same that part a)</em>