They are adding steel components to the roof supports of the structure. we know that steel elongates when heated. at what temperature will steel elongate nine inches per 100 feet of length?
a) 500 degrees.
b) 1000 degrees.
c) 1500 degrees.
d) 2000 degrees.

The change in temperature of 576.9°C will produce an elongation of 9 inches per feet in steel.

Explanation:

The formula for linear expansion of a material is:

ΔL = αLΔT

where, ΔL = change in length

             L = Original length

           ΔT = Change in temperature

             α = coefficient of linear expansion

For steel, α = 13 x 10^-6 /°C

                L = 100 ft

                ΔL = (9 in)(1 ft/12 in) = 0.75 ft

Therefore,

0.75 ft = (13 x 10^-6 /°C)(100 ft)ΔT

ΔT = 576.9°C

when a device is used in a circuit in which the voltage is 81 v, the current flowing through the device is 3 a. what is the resistance of the device?

a. 27 ω

b. 40.5 a

c. 243 ω

d. 243 a

the correct answer is a. 27