A 6kg bucket of water is being pulled straight up by a string at a constant speed.

I determined that the tension on the string was

F = ma

F = (6kg * 9.8 m/s²) * 0a
F = 58.8 N

Now its asking

At a certain point the speed of the bucket begins to change. The bucket now has an upward constant acceleration of magnitude 3 m/s². What is the tension in the rope now?

The correct answer was "about 78N"

I dont understand how this 78 N was calculated, my mass (6 * 9.8) stayed the same and a=3, so i would have figured it would be at least closer to (6 * 9.8) 3 = 176.4 N.

What am I missing?