The copper windings of a motor have a resistance of 50 Ω at 20° C when the motor is idle. After the motor has run for several hours the resistance rises to 58Ω. What is the temperature of the windings now? (Ignore changes in the dimensions of the windings).

The temperature of the windings are 60.61 °C

Explanation:

Step 1: Data given

Resistance = 50 Ω

Temperature = 20.0 °C

After the motor has run for several hours the resistance rises to 58Ω.

Step 2: Calculate the new temperature

Formula: R = Rref(1 + α(T-Tref))

⇒with α = temperature coëfficiënt of Cupper at 20 °C = 0.00394/°C

⇒with Tref = reference temperature = 20°C

⇒with T = end temperature = TO BE DETERMINED

⇒with R = resistance at end temperature = 58Ω

⇒with Rref = resistance at reference temperature =  50 Ω

==> T = (R/Rref - 1)/α + Tref  

T = (58/50) - 1 )/ 0.00394 + 20

   T = 60.61 °C

The temperature of the windings are 60.61 °C

false br

answer;

d. are made mostly of liquid

explanation;

-the general   composition and structure planets includes; they have a thick gas and liquid layer covering a small,solid core. mostly the gases are hydrogen and helium atmosphere and layers of liquid hydrogen. for instance neptune and uranus are examples of the outer planets, they have a core covered by ice and ammonia.

-neptune's atmosphere is hydrogen and helium with a bit of methane so there is no oxygen to breath and the interior is made up of frozen water and ammonia with a rock and iron core. thus, there is no liquid water or solid surface to survive.