FOR A liquid drop of radius r falling in air with terminal velocity, power delivered by gravitational force is propotional to

P = m g v

Explanation:

Power is defined as the relationship between work and time

        P = W / t

The work is defined by the scalar product of the force and the displacement, in the case of a drop falling the vertical force and the displacement has the same direction, therefore the angle between them is zero and the cosines of zero is one (cos 0 = 1)

       W = F y

the gravitational force is proportional to the weight of the drop  (F = mg)

        W = mg y

we substitute

       P = m g y / t

the terminal velocity of the drop is constant

       P = m g v

a.metals can become magnetic if they have many spinning electrons that create magnetic fields.d.only some metals are attracted by magnets; these metals are called ferromagnetic.

d.wrapping an insulated wire around a metal with ferromagnetic properties and applying an electric current.