## Tuesday, March 03, 2009

### Break a Rope

Under what conditions would a rope be most likely to break?

a. 20 men of equal strength with 10 pulling on each end.
b. 10 of the same men pulling on one end and the other end being fastened to a tree.
c. It makes no difference.

1. c. .... I think. Newton helps us here.

2. I think its c. because if 10 men where to pull on a tree, the tree would be exerting an equal but opposite force, taking on the exact roll of the 10 men on the other side in choice a.

3. As usual, I can't fool you. C is the answer, as explained above by you.

4. the answer should be (B)The tree would be stiff offering little if any give(depending on tree size and placement of the rope)(A)10 men pulling in oppisite directions would tend to heave & hoe thus giving less resistance and fluxuation of stress on the rope.

5. This comment has been removed by the author.

6. you didnt give any tree description..

so..

it can be b or c..

a and c makes no difference..

but you need to break the rope..

but the answer depends on what type of tree..

7. C. the tree doesn't exert any force. contradicting to the men forces. :]

8. The answer being C is actually incorrect. It is in fact A. 10 people pulling in one direction, whether the other end is attached to a tree, brick wall, house, or any other non-moving in-animate object can only exert the force of 10 people. The tree/wall/house/whatever can exert no force of its own. Contrast this with 10 people pulling in one direction and 10 pulling in the other, maintaining that every single person exerts the exact same force, and you obtain double the pulling power of 10 people. Thus, the rope has a greater chance to break under teh combined pulling force of 20 people. It really is simple mathematics.

9. My previous comment was actually incorrect as I was misusing Newton's third law. C would actually be the correct answer as the tree would exert a force equal to those pulling on the rope. If however 20 people were pulling on one side of the rope, the rope would break more easily and this is what I was thinking. Direction does in fact matter.

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