Difficult time with motion graphs & dynamics

[devilish_wit]

Homework Statement

The figure below shows the speed of a person's body as he does a chin-up. Assume the motion is vertical and the mass of the person's body is 72.7 kg. Determine the force exerted by the chin-up bar on his body at the following times.

My answers:

Homework Equations

F = ma

The Attempt at a Solution

I'm not quite sure how to solve that last part:

I solved for the acceleration at 1.6s which is -60m/s^2.

F = ma
-mg + T = m a
T = 72.7kg(60m/s^2) + (9.8m/s^2)(72.7kg)
T = 3649.54?? (this one's wrong)

 

[devilish_wit]

oh never mind guys, I realized I made a stupid mistake. My acceleration was in cm/s and not in m/s!