THE CANTILEVER

You will be provided with a hinged cantilever device consisting of a base and a hinged cantilever beam. The beam will be supported at the bottom by a hinge and by several threads attached to a screweye near the midpoint of the beam and to a screweye on the base. It is the task of your engineering firm to determine the minimum number of threads required to support the beam at a 45o angle when loaded with a freely hanging 2 kg mass attached to the screweye at the top of the beam. Time will be an important consideration for this lab. It is highly recommended that you work the problem 11.13 b, listed in the homework assignment before  the lab session.

 

You are allowed (but not necessarily limited) to do the following:

  1. Make any measurement of the beam and base you wish. You may put marks on the beam with the soft-tipped pens provided (remove with alcohol when finished). The beam can be removed from the base by removing the hinge pin.
  2. Test a single length of thread for strength and elasticity. You may perform a test any number of times.
  3. Perform any calculation.
  4. Ask the Master Consultant (intructor) questions.

You are forbidden to do the following:

  1. Test more than one thread at a time.
  2. Test your final calculations with the cantilever system.
  3. Consult with the "other" engineering firms.

The winning engineering firm will be determined at the end of the exercise. The cantilever must support the 2 kg load at 45o or less from the horizontal for 30 seconds after the load is applied. A firm will be disqualified if the threads break before the end of the 30 seconds. In determining the winner(s), a penalty will be assessed if the beam angle is greater or less than 45o.

Report

Each firm will submit one report. Completely document every measurement and calculation you make. Show all measurents clearly in a diagram of the cantilever device. In your report, discuss all the elements you considered in making your final decision. Which elements did you actually use, which did you ignore, and why? Describe any difficulties you had while making measurements and discuss the sources of errors.