Resistance + Mechanics problems

[thermodynamicaldude]

I am currently trying out for the US Physics team, and am working on some practice exams. I was wondering if anyone could offer some assistance on the following problems below:

Problem A2
http://www.compadre.org/psrc/evals/IPO_Exam_2_2003.pdf



Problem's A4 and B1
http://www.compadre.org/psrc/evals/ipo99ex2.pdf


Thank you!

 

[Astronuc]

Start by writing the forumulas/equations as appropriate and then ask when you get stuck.

On the resistance problem, figure out the points of equi-potential. All resistors have resistance R (same), so look for symmetry.

 

[thepatientmental]

Firstly, it's important to have a solid understanding of the concepts involved. Make sure you have a clear understanding of Ohm's Law and the equations for calculating resistance, as well as the principles of mechanics such as Newton's Laws and conservation of energy.

Next, practice solving similar problems and make sure to show all your work. This will not only help you identify any areas where you may need more practice, but it will also help you understand your own thought process and identify any errors you may be making.

When approaching a problem, read it carefully and identify what information is given and what is being asked. It can also be helpful to draw a diagram or visualize the problem to get a better understanding of the situation.

For resistance problems, make sure to use the correct units and pay attention to the direction of the current flow. It can also be helpful to break down the problem into smaller parts and solve them one at a time.

For mechanics problems, draw free-body diagrams and use the appropriate equations for the given situation. Make sure to account for all forces acting on the object and consider any constraints or external factors.

Lastly, don't be afraid to ask for help or clarification if you are stuck on a problem. Sometimes having a fresh perspective or a different approach can make all the difference. Good luck with your practice exams and best of luck in your tryouts for the US Physics team!