How much power is required to raise a 200-kg crate a vertical distance of 2 meters in a time 4 seconds?

Couple of concepts to get down:

1. Power is equal to the work done per unit time. Alteratively, it's also equal to the force being applied to an object times the velocity of the object.

2. The work done is equal to the force applied to the object times the distance it moves. In lifting an object at constant velocity the force required is equal to the weight of the object F=mg.

So, here you have a 200 kG weight being hoisted 2 meters. Multiply its weight by the distance to get the work done to lift it, then divide by time (4 seconds) to get the power required to do it in 4 seconds. Or alternatively, multiply the force F = mg times the velocity of the object, which is 2 meters/4 seconds. Both approaches should give you the same answer.