Force On Object With Constant Speed

[ptguard1]

A sack of flour of mass 6.00 kg is lifted vertically at a constant speed of 4.00 m/s through a height of 18.0 m

How great a force is required?

F=ma


I found the force that the sack has on the Earth (58.8N), but don't understand how I am suppose to find what force is being applied to the sack in order to give it a constant speed of 4.00 m/s.

 

[ptguard1]

I figured out that the force is equal to the 58.8 N of force that the sack had on the earth. My logic was that an object can be lifted at different speeds with the same force, is this true or only partially true?

 

[Inferior89]

As long as the speed of the object is constant the total forces on the object should add up to 0. Since the gravitational field is pretty much constant at the altitude differences you have in your problem you just need to add the same force as the gravitational force.