A certain material is in a room at 25°C. If the absolute temperature (K) of the material is tripled, its resistance doubles. (Water freezes at 273 K.) What is the value for α, the temperature coefficient of resistivity?

The temperature coefficient of resistivity is 0.001689 /°C

Explanation:

Given initial temperature = 25°C = 25 + 273 = 298 k

The final temperature = Three times = 3

Resistance at =  

Resistance at ()= double resistance at = 2  

The resistance of a body can be obtained when given the above parameters with the expression below;

...............................1

Inputting the parameters into equation 1 we have;

2   =  

isolating α we have;

α = 1/(2 x 298 k)

α = 1/596

α = 0.001678 /K = 0.001689 /°C (change in temperature is the same at both centigrade and kelvin scale.

Therefore the temperature coefficient of resistivity is

0.001689 /°C

what was the answer?

see the picture for the vector

the magnitude of the vector by pythagorean theorem

r = √( (-10)^2 + (3)^2 ) = √109

magnitude = √109 units

the direction angle between vector and x-axis is

tan^(-1)(3/10) = 16.699

so the direction is approximately 16.7 degrees north of west