the fact that it is saying one side weighs more than the other and the rope is equal length does defy physics.

You are assuming a very large coefficient of friction, one much larger than any fence/rope that I know of. The problem itself is wrong. that was the point I was trying to make. The correlations it is making can't happen with the way the problem is worded.

 

he creates a ratio of 4/9 without explaining where it came from. With some backwards math I was able to see where he pulled it from. My way of writing the problem was still more simple and easier to understand. even though they equal each other. His lack of units makes it more difficult to understand.

 

Maybe the simplfied version of physics you know, but reality is a bit more complex.

You don't believe me do you? go out and try it yourself-

Take any length of rope and throw it over a 2X4, put a pound weight on each side, and add weight to one side until it slips, unless you have very slippery rope, I don't think its going to move untill you have at least a 2:1 ratio between the two sides weights.

 

you are assuming it is a wood fence. What if it is a chainlink fence, the coefficient of static friction will be less. You are making assumptions in order to make it work for you. You can't do that. You need to go with what is given. You can't just assume there is going to be a very large coefficient of friction between the fence and the rope.


bah, i am done arguing about this, it is pointless, I have more important things to do.

 

It's Very Simple!!! The Bananna Will Not Fly.

 

What is given is

A rope over the top of a fence has the same length on each side

This point is actually irrelevent

and weighs 1/3 of a pound per foot.

On one end hangs a monkey holding a banana, and on the other end a weight equal to the weight of the monkey.

Nowhere does it say that they are in balance or that they are equal in weight- in fact it is implied by the statement above that they are not of equal weight because it states the monkey is holding a banana, not "might be holding a banana" or is holding a weightless banana.

YOU are the one making things up and changing the conditions of the problem statement.


OK, still you're wrong.

 

Here is an even more detailed proof, along with why the weightless banana doesn't work either:

Monkey's age: x
Monkey's weight: w oz
Monkey mother's age: y
Rope's length: r ft
Rope's weight: 1/3 lb/ft = 4/9 oz/in
Banana length: b in
Banana's weight: 2b oz


A rope over the top of a fence has the same length on each side

(Like I said- this point is actually irrelevent)

and weighs 1/3 of a pound per foot.

Rope's weight: 1/3 lb/ft = 4/9 oz/in

On one end hangs a monkey holding a banana, and on the other end a weight equal to the weight of the monkey.


The banana weighs 2 ounces per inch.

Banana length: b in
Banana's weight: 2b oz


The length of the rope in feet is the same as the age of the monkey

(1) r = x

and the weight of the monkey in ounces is as much as the age of the monkeys mother.

(2) w = y

The combined ages of the monkey and its mother are 30 years.

(3) x + y = 30

1/2 the weight of the monkey plus banana is 1/4 the sum of the weights of the rope and the weight.

(4) (1/2)w + 2b = (1/4)[(4/9)(12r) + w]

The monkeys mother is 1/2 as old as the monkey will be when it is 3 times older as old as its mother was when she was 1/2 as old as the monkey will be when it is as old as its mother will be when she is 4 times as old as the monkey was when it was twice as old as its mother was when she was 1/3 as old as the monkey was when it was as old as its mother was when she was 3 times as old as the monkey was when it was 1/4 as old as it is now.

(5) y = (1/2)(3)(1/2)(4)(2)(1/3)(3)(1/4)x

From (5):
y = (3/2)x

Substitute y = (3/2)x into (3):
x + (3/2)x = 30
(5/2)x = 30
(5/2)x * (2/5) = 30 * (2/5)
x = 12

Solve for y, r, w, and b:
y = 18
n = 12
w = 18

Substitute r = 12 and w = 18 into (4):
(1/2)(18) + 2b = (1/4)[(4/9)(144) + 18]
9 + 2b = 41/2
2b = 23/2
b = 23/4

The length of the banana is 23/4 inches or 5.75 inches long.


Now, try the math with a weightless banana:

Substitute y = (3/2)x into (3):
x + (3/2)x = 30
(5/2)x = 30
(5/2)x * (2/5) = 30 * (2/5)
x = 12

Solve for y, r, w, and b:
y = 18
n = 12
w = 18

Substitute r = 12 and w = 18 into (4), but set b=0
(1/2)(18) +2(0)= (1/4)[(4/9)(144) + 18]
9 = 41/2

Which is false.

I’m sorry you are a math and logic hater Ryan, they are good tools to help understand how the world works

 

It's an airplane cabin!!!!

 

Yes, that is exactly why I got my degree in Mechanical Engineering, to hate on math.

 

Uh...hypothetical questions for the sake of doing algebra do NOT require strict adherance to the laws of physics.

This is not a question on an engineering exam, or even a science test. It is explicitly stated as a math problem.

 

That is what I hated about all my math classes, too much stuff that makes no sense in the real world.