Incorrect answers in MERM PP edition 12???

[goodal]

I think I have found two problems with the MERM PP edition 12 second printing. These arent in the errata on the PPI site.

Probelm 40.7: to find the heat loss for the 68F temp indoors they used the q/delta t using 70F. Shouldnt they have used 200000/68F instead of 200000/70F in the last part?

Problem 49.2: They used ymax for both forces, meaning both deflections were taken from the end. Shouldnt they have used the equation for yx which calced the deflection at the distances given then add the slope to each?

 

[goodal]

No takers???

 

[MechGuy]

I would need to see the question as I don't have the Practice problems book anymore. I only kept the MERM after the exam.

 

[MikeR]

I think I have found two problems with the MERM PP edition 12 second printing. These arent in the errata on the PPI site.
Probelm 40.7: to find the heat loss for the 68F temp indoors they used the q/delta t using 70F. Shouldnt they have used 200000/68F instead of 200000/70F in the last part?

Problem 49.2: They used ymax for both forces, meaning both deflections were taken from the end. Shouldnt they have used the equation for yx which calced the deflection at the distances given then add the slope to each?

The design heat loss of 200,000 Btu/hr was originally based on 70F indoor and 0F outside temp. Therefore when you lower the thermostat from 70 to 68F, to calculate heat loss per degree of temp.

using the 200,000 Btu/hr the original value of 70F should be used.

 

[goodal]

That makes sense. I was thinking the 70F was the indoor temp.