What would happen if all the propellers on a quadcopter rotated in the same direction?

A. The quadcopter would spin because the net torque would not be zero.
B. The quadcopter performs a roll maneuver.
C. The front of the quadcopter would pitch up or down.
D. If all the propellers rotated clockwise, then the quadcopter would spin clockwise as well.

Awall of 0.5m thickness is to be constructed from a material which has average thermal conductivity of 1.4 w/mk. the wall is to be insulated with a material having an average thermal conductivity of 0.35 w/mk so that heat loss per square meter shall not exceed 1450 w. assume inner wall surface temperature of 1200°c and outer surface temperature of the insulation to be 15°c. calculate the thickness of insulation required.

A3-mm-thick panel of aluminum alloy (k 177 w/m-k, c 875 j/kg-k and ? = 2770 kg/m) is finished on both sides with an epoxy coating that must be cured at or above t,-150°c for at least 5 min. the production line for the curing operation involves two steps: (1) heating in a large oven with air at ts,0-175°c and a convection coefficient of h, 40 w/m2. k, and (2) cooling in a large chamber with air at 25°c and a con- vection coefficient of he 10 w/m2.k. the heating portion of the process is conducted over a time interval te which exceeds the ime required to reach 150°c by 5 min (h = r + 300 s). the coating has an emissivity of ? = 0.8, and the temperatures of the oven and chamber walls are 175 and 25°c, respectively. if the panel is placed in the oven at an initial temperature of 25°c and removed from the chamber at a safe-to-touch tempera ture of 37°c, what is the total elapsed time for the two-step curing operation?

Asimple rankine cycle uses water as the working fluid. the water enters the turbine at 10 mpa and 480c while the condenser operates at 6 kpa. if the turbine has an isentropic efficiency of 80 percent while the pump has an isentropic efficiency of 70 percent determine the thermal efficiency