Tension Strongman problem from Physics

havechanged

Tension "Strongman" problem from Physics!!

This is the question:
When the strongman suspends the 10 lbs telephone book with the rope held vertically, the tension in each strand of the rope is 5 lbs. If the strongman could suspend the book from the strands pulled horizontally, the tension in each strand would be how much?

A picture of it is at this website: http://www.physics.uwo.ca/ugrad/p02.../p021_lec12.pdf [Broken] with a picture of a guy holding a textbook.

Any answers? And reasons for the answers?

Thanks!

Last edited by a moderator:
Related Introductory Physics Homework Help News on Phys.org

HallsofIvy

Homework Helper
I wasn't able access the website given. Since the telephone book weighs 10 pounds and we are told that the "tension in each strand" is 5 pounds, are we to assume there are 2 strands?

It isn't possible to support the book with strands that are literally horizontal- there would be no vertical component of force.

Assuming that the two ropes make angle &theta; with the horizontal and have tension T, then the vertical component of force for each strand is T sin(&theta;)- the two together 2 T sin(&theta;) and that must be 10 pounds: 2 T sin(&theta;)= 10 so T= 5/sin(&theta).

havechanged

Thanks!

I hope you didn't spend too much time doing that! The answer did turn out to be an uncalculatable amount- it is impossible to make it perfectly straight. My teacher mentioned how power lines are bent down too...

Last edited:

Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving