phsyics help!!?

Linear thermal expansion equation :

http://en.wikipedia.org/wiki/Coefficient_of_therma...

the triangle is called delta meaning change.

So the equation goes as following:

(change in length) / (original Length) = (thermal expansion coefficient) * (change in temperature)

For number 1:

change in Length = unknown, we will solve for this

original Length = .4 meters, 40cm equal .4 meters

thermal expansion coefficient = 17 * 10^-6, it's from a table you look up, for copper it's about 17 * 10^-6

change in temperature = 100, since it went from 20 degree to 120

(change in Length)/(.4) = (17 * 10^-6) * (100)

some simple algebra :

change in length = 6.8 * 10^-4 meters

You wanted the final length so (original length) + (change in length) = final length

Final Length = .40068 meters

For number 2:

Can be done similarly but with the Area thermal expansion equation:

(change in area) / (original area) = 2 * (thermal expansion coefficient) * (change in temperature)

Notice there is now a 2 infront of the thermal expansion coefficient

thermal expansion coefficient of aluminum is 23 * 10^-6 according to wikipedia

I'll leave it to you to do the rest

Hi;

1-(Delta)L=@L_1(D)T

(D)T=100

L_1=40x10^-2 m

@(COOPER)=17x10^-6

(D)L=17x10^-6x40x10^-2x10^2

(D)L=680x10^-6 m

L_2=L_1+(D)L

L_2=(680+400000)(10^-6)

L_2=400680 (Micro Meter)

L_2=400680x10^-6 m

..................................................

(D)A=2@A_1(D)T

@(Al)=23x10^-6

A_1=80x30x10^-4=0.24 m^2

(D)T=145-35=110

(D)A=2x23x10^-6x0.24x110

(D)A=1214.4x10^-6

A_2=A_1+(D)A

A_2=(1214.4+240000)(10^-6)

A_2=241214.4x10^-6 m^2

....................................................

Hope you Bests!