Dynamics Problem

1. Mar 30, 2005

jen333

Hey!
I have a physics problem on dynamics. I did the question and received an answer, however, the answer is different from the one that i was given. I just want to know if I did something wrong (i probably did) or if the answer that was given is wrong. here it goes:

Proper storage of hay bales is essential for the survival of cattle during Canadian winters. A farmer uses a cable to exert an upward pull of 850N on a 81.6kg bale of hay at a local farm. Use a diagram and determine the acceleration of the bale as it is lifted onto a barn loft.
The answer that is given is 0.607m/s^2

Here's how I executed the problem:
a) drew a FBD diagram
^
l
l
l T=850N
O
l
\/ Fg

b) i found the force of support on the bale of hay (not sure if this is right)
F=ma
= 81.6kg x 9.81m/s^2
= 800N

c) subtracted this force from the tension force:
850N-800N= 50N

d) i used the formula again F=ma

a=F/m= 50N/81.6kg
= 0.613m/s^2

2. Mar 30, 2005

whozum

Considering you are off by 0.06m/s^2 I would say your error is from rounding.

In part b) 81.6 x 9.81 = 800.496

850 - 800.496 = 49.504

49.504/81.6 = 0.606666666m/s^2

3. Mar 31, 2005

jen333

alright! good to know that i'm on the right track
Thx for the help!

jen