You are a thief and you want to lower yourself from the rooftop to a second floor window, which is at a distance H=12m below the tip of the roof. You want to use a nylon rope, which has a failure stress of 400 MPa, and a Young’s modulus of 1 GPa. If you weigh 225 lb, what diameter rope, Dmin, should you choose if you want a safety factor of 2 against failure?
2.4
10
Thanks Sat, but can you write your reasoning behind the answer?
Rotating blade (body force in axial loading)
A blade is fixed to a rigid rotor of radius R spinning at omega rad/sec around the vertical z-axis (see figure). Neglect the effects of gravity.
Calculate the peak stress in the blade: sigma_max_n
Calculate the blade elongation: delta
Calculate the displacement of the blade mid-section: u_x(L/2)
sigma max n =
delta =
u_x(L/2) =