Forces question HELP!

[wr1015]

When you lift a bowling ball with a force of 82 N, the ball accelerates upward with an acceleration a. If you lift with a force of 99 N, the ball's acceleration is 8 x a.
(a) Find the weight of the bowling ball.
N
(b) Find the acceleration a.
m/s2


Ok, i found part (a), which is 78.48 N. Now, on part (b) why wouldn't the acceleration be 99 N/ 8 kg, which is 12.37 m/s2????

 

[Doc Al]

What's the net force on the ball?

 

[HallsofIvy]

Did you forget that you have to lift with the weight of the ball just to get it moving at all? The force in "F= ma" is 99N- mg.

As usual, Doc Al got there before me!