If the rate of change of the magnetic field applied to a loop of wire is doubled, what happens to the induced emf in that loop assuming that all other parameters remain unchanged?

It is doubled.

Explanation:

The EMF( Electromotive force) is usually gotten from an energy source. In this case it is from the magnetic field. However when the other parameters are constant then the main focus is between the EMF and the magnetic field. They have a direct proportion relationship which is why when the magnetic field is doubled the EMF is doubled too.

weight of the box is given as

here this is placed on the inclined of angle 42 degree

now this weight will have two components one is along the incline other is perpendicular to it

so here we need to apply a force parallel to incline opposite to its component of weight

so here the component of weight is given as

here we have

so it requires 75 n force to move it upwards

t = 1/400 h   ⇔ 0.0025 h ⇔ 9s ⇔ 0.15 m

any of the answers are correct.