It takes a crane 60 seconds to lift a 150kg box from the ground to the top of a 100m tall building. Calculate the magnitude of power exerted by the crane to lift the box A. 9 x 109 W

B. 9 x 109 N

C. 2450 W

D. 2450 N

E. None of the above

Explanation:

Power equals the amount of work done divided by the time it takes to do the work (in seconds). Work itself is equal to the amount of force it takes to move an object a certain number of meters. We are given the mass of the object. Since force is a measure in Newtons, and we are given mass, we need to use the mass to find the weight of the object, since weight is a force and is measured in Newtons!

F = weight = 150(9.8) so

F = 1470. Now we will use that along with the displacement in the Power equation:

P = [1470(100)]/60 so

P = 2450 Watts, choice C.

the answer is the first electromagnet (a). this is because it has more coils around the ferromagnetic material. increasing the number of coils increases the surface area in which the metal interacts with the current in the coil. this enables more atoms in the metal to become aligned hence becoming more magnetized.