4: 4-21

Problem: In order to pull out the nail at B, the force F exerted on the handle of the hammer must produce a clockwise moment of 500 lb * in about point A. Determine the required magnitude of force F.

Variable Solution:

Givens: 
a = 18 [in]
b = 5 [in]
α = 30
M_A = 500 [lb⋅in] CW
**notice that M_A is clockwise so it will be negative in our numerical solution, because it goes into the page

Numerical Solution:
F = -M_A/(bsinα+acosα)
→-(-500 [lb⋅in]) / ((5 [in])sin(30)+(18 [in])cos(30))
F = 27.64 [lb]