Answer:
i) The torque required to raise the load is 15.85 N*m
ii) The torque required to lower the load is 6.91 N*m
iii) The minimum coefficient of friction is -0.016
Explanation:
Given:
dm = mean diameter = 0.03 m
p = pitch = 0.004 m
n = number of starts = 1
The lead is:
L = n * p = 1 * 0.004 = 0.004 m
F = load = 7000 N
dc = collar diameter = 0.035 m
u = 0.05
i) The helix angle is:
![tan\alpha =\frac{L}{\pi *d_{m} } =\frac{0.004}{\pi *0.03} \\\alpha =2.43](https://tex.z-dn.net/?f=tan%5Calpha%20%3D%5Cfrac%7BL%7D%7B%5Cpi%20%2Ad_%7Bm%7D%20%7D%20%3D%5Cfrac%7B0.004%7D%7B%5Cpi%20%2A0.03%7D%20%5C%5C%5Calpha%20%3D2.43)
The torque is:
![T=F\frac{d_{m} }{2} (\frac{\pi *u*d_{m}+L }{\pi *d_{m}-uL } )+(u_{c} F+\frac{d_{2} }{2} )=7000*\frac{0.03}{2} (\frac{\pi *0.05*0.03+0.004}{\pi *0.03-0.05*0.004} )+(0.05*7000*\frac{0.035}{2} )=15.85Nm](https://tex.z-dn.net/?f=T%3DF%5Cfrac%7Bd_%7Bm%7D%20%7D%7B2%7D%20%28%5Cfrac%7B%5Cpi%20%2Au%2Ad_%7Bm%7D%2BL%20%7D%7B%5Cpi%20%2Ad_%7Bm%7D-uL%20%7D%20%29%2B%28u_%7Bc%7D%20F%2B%5Cfrac%7Bd_%7B2%7D%20%7D%7B2%7D%20%29%3D7000%2A%5Cfrac%7B0.03%7D%7B2%7D%20%28%5Cfrac%7B%5Cpi%20%2A0.05%2A0.03%2B0.004%7D%7B%5Cpi%20%2A0.03-0.05%2A0.004%7D%20%29%2B%280.05%2A7000%2A%5Cfrac%7B0.035%7D%7B2%7D%20%29%3D15.85Nm)
ii) The torque to lowering the load is:
![T=7000*\frac{0.03}{2} (\frac{\pi *0.05*0.03-0.004}{\pi *0.03+0.05*0.004} )+(0.05*7000*\frac{0.035}{2} )=6.91Nm](https://tex.z-dn.net/?f=T%3D7000%2A%5Cfrac%7B0.03%7D%7B2%7D%20%28%5Cfrac%7B%5Cpi%20%2A0.05%2A0.03-0.004%7D%7B%5Cpi%20%2A0.03%2B0.05%2A0.004%7D%20%29%2B%280.05%2A7000%2A%5Cfrac%7B0.035%7D%7B2%7D%20%29%3D6.91Nm)
iii)
![T=F\frac{d_{m} }{2} (\frac{u*\pi *d_{m}-L}{\pi *d_{m}+uL} )+u_{c} *F*\frac{d_{c}}{2}\\ 0=F\frac{d_{m} }{2} (\frac{u*\pi *d_{m}-L}{\pi *d_{m}+uL} )+u_{c} *F*\frac{d_{c}}{2}\\F\frac{d_{m} }{2} (\frac{u*\pi *d_{m}-L}{\pi *d_{m}+uL} )=-u_{c} *F*\frac{d_{c}}{2}\\\frac{d_{m} }{2} (\frac{u*\pi *d_{m}-L}{\pi *d_{m}+uL} )=-u_{c} *\frac{d_{c}}{2}\\\\\frac{0.03}{2} (\frac{u*\pi *0.03-0.004}{\pi *0.03+u*0.004} )=-0.05*\frac{0.035}{2}](https://tex.z-dn.net/?f=T%3DF%5Cfrac%7Bd_%7Bm%7D%20%7D%7B2%7D%20%28%5Cfrac%7Bu%2A%5Cpi%20%2Ad_%7Bm%7D-L%7D%7B%5Cpi%20%2Ad_%7Bm%7D%2BuL%7D%20%29%2Bu_%7Bc%7D%20%2AF%2A%5Cfrac%7Bd_%7Bc%7D%7D%7B2%7D%5C%5C%20%200%3DF%5Cfrac%7Bd_%7Bm%7D%20%7D%7B2%7D%20%28%5Cfrac%7Bu%2A%5Cpi%20%2Ad_%7Bm%7D-L%7D%7B%5Cpi%20%2Ad_%7Bm%7D%2BuL%7D%20%29%2Bu_%7Bc%7D%20%2AF%2A%5Cfrac%7Bd_%7Bc%7D%7D%7B2%7D%5C%5CF%5Cfrac%7Bd_%7Bm%7D%20%7D%7B2%7D%20%28%5Cfrac%7Bu%2A%5Cpi%20%2Ad_%7Bm%7D-L%7D%7B%5Cpi%20%2Ad_%7Bm%7D%2BuL%7D%20%29%3D-u_%7Bc%7D%20%2AF%2A%5Cfrac%7Bd_%7Bc%7D%7D%7B2%7D%5C%5C%5Cfrac%7Bd_%7Bm%7D%20%7D%7B2%7D%20%28%5Cfrac%7Bu%2A%5Cpi%20%2Ad_%7Bm%7D-L%7D%7B%5Cpi%20%2Ad_%7Bm%7D%2BuL%7D%20%29%3D-u_%7Bc%7D%20%2A%5Cfrac%7Bd_%7Bc%7D%7D%7B2%7D%5C%5C%5C%5C%5Cfrac%7B0.03%7D%7B2%7D%20%28%5Cfrac%7Bu%2A%5Cpi%20%2A0.03-0.004%7D%7B%5Cpi%20%2A0.03%2Bu%2A0.004%7D%20%29%3D-0.05%2A%5Cfrac%7B0.035%7D%7B2%7D)
Clearing u:
u = -0.016
please give a better explanation of what you want to be answered.
Answer:
SIR IT IS D HOPE THIS HELPS (☞゚ヮ゚)☞☜(゚ヮ゚☜)
Explanation:
Answer: Photo lines
Explanation: made more sense