Balancing Forces on a Scale: Man with Pulleys and Tensions

[wah31]

Homework Statement

Man standing on scale and pulling on a rope connected to two pulleys

Homework 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..

 

[oz93666]

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

 

[wah31]

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

 

[haruspex]

Homework Statement

Man standing on scale and pulling on a rope connected to two pulleys

Homework 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..

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.

 

[wah31]

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

 

[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

 

[wah31]

Yes you are right

Thank you.. it's cool

 

[haruspex]

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

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