# Homework Help: Man standing on a scale

1. Jan 5, 2017

### wah31

1. The problem statement, all variables and given/known data
Man standing on scale and pulling on a rope connected to two pulleys

2. Relevant equations
The mass of the man is: m=100 kg

The weight of the pulleys, cables, balance, and the frictions are not taken into account

g=10m x s-2

3. The attempt at a solution

the force that the man should draw in order to maitain balance:
T1=250 N

The weight displayed on the scale:
P= 125 kg

Other tensions:
T2=250 N
T3=500 N
T4=500 N
T5=1000 N

Do your agree with that ?
Thank you..

#### Attached Files:

• ###### Balance-page-001.jpg
File size:
5.7 KB
Views:
72
Last edited: Jan 5, 2017
2. Jan 5, 2017

### oz93666

You have not laid out the question properly ... what information is given in the question?

3. Jan 5, 2017

### wah31

You just have to validate or not thes values (T1, P, T2, T3, T4, T5)

4. Jan 5, 2017

### haruspex

I agree with all the tensions, but I do not understand how you got 125kg for the scale reading. Consider again which way the forces act on the man.

5. Jan 5, 2017

### wah31

I'm not convinced either
I thought about it..

6. Jan 5, 2017

### oz93666

Yes I agree there is something wrong

What do we know for sure ? ....T1= T2 and T3 =T4 ...... 4xT1 = 2xT4 = T5 and T5 is supporting all the mass = 100kg = 1000N ... so all the tensions are correct .

The weight indicated on the scale must be the man's weight , minus the the pull from T1 .... 1000 - 250 = 750N scale should indicate 75Kg not 125kg

7. Jan 5, 2017

### wah31

Yes you are right

Thank you.. it's cool

8. Jan 5, 2017

### haruspex

This is a homework forum. We point out errors, provide hints, explain principles.... We do not post solutions.