So basically I don't understand why my solutions to this problem are wrong and I don't know how to calculate the normal force. If someone could explain why my answers are wrong and explain the normal force part that would be great. The problem is given as follows:

"A man having a weight of 175 lb attempts to hold himself using one of the two methods shown. Determine the total force he must exert on bar AB in each case and the normal reaction he exerts on the platform at C. Neglect the weight of the platform." the diagram given (The diagram has all the relevant info, it's not that complicated)

My solution: my solution The answers in the text are a) F=175 lb, N =350 and b) F=87.5 lb, N=87.5 lb. I don't understand why my answers are basically reversed.

  • 2
    $\begingroup$ When you push down or pull up on the bar it should effect the apparent weight of the person. Draw free body diagrams for the person, you should see what I mean. $\endgroup$
    – JMac
    Apr 7, 2017 at 16:05
  • $\begingroup$ You can not take down ward force as W in any case that is what you have to find, N ! $\endgroup$ Apr 7, 2017 at 16:21

1 Answer 1


JMac was very helpful, thanks man. I successfully solved it. You can see my solution at https://i.stack.imgur.com/zovG4.jpg if you're interested.

  • 1
    $\begingroup$ Glad you were able to solve it. May I recommend that you write the solution up properly - we would be able to upvote your answer and you can then "accept" it as well. All of which will get you some recognition for the work you did. A "link-only answer" (which this currently is) usually ends up being deleted and that would be a shame. $\endgroup$
    – Floris
    Apr 7, 2017 at 19:15
  • $\begingroup$ I don't have the time unfortunately. $\endgroup$
    – Steeves
    Apr 8, 2017 at 3:04

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.