Answer:
Powerful electromagnets are fitted on top of guideways either ttract or repel the magents fitted on the bottom of train. The froce of attraction/repulsion rasies the train in hovering position.
Explanation:
Magentic fields exist between two opposite/like poles. The poles do not have to be touching each other. They can be separated by a distance in a medium that doesn' block magnetic field.
In magelv train the magnetic forces between two poles are used to operate the train. The two poles are separated by train body and air.
However here coefficient of friction is not given so unable to calculate.
You can calculate it by below formula.
The formula given by

Or

u is coefficient of friction
N is normal reaction.
Here..
box doesn't move means the force if limiting friction is greater than applied force.
Answer:
I think this is how you do it
Explanation:
They would melt because the heating of platinum that showed air was absorbed into its pores as it was heating, thus weakening the metal and causing it to melt at low temperatures