A rock, shaped like the rock sits in a desert in Iraq. The rock has a surface area of 3m^2, and heats up to 55C during the day. The air temperature at night is 10C. IF the rock gives off heat at a power of 10C. If the rock gives off heat at a power of 140W, what is the emissivity of the rock.

Afoot bridge is made as a simple deck, 4 m long, with a cross section 2 m (wide) and 20 cm thick, and made of wood. the deck is supported at the two ends. the maximum load allowable on the bridge is 10 tons, provided it is uniformly distributed on the deck. to sense this load, a strain gauge is placed at the center of the bridge and its resistance is monitored. if the sensor has a nominal resistance of 350 s2 and a gauge factor of 3.6, what is the reading of the strain gauge at maximum load? the modulus of elasticity for the wood used in the construction is 10 gpa.