Physics 21 Thermal Expansion (2 of 3) Thermal Area Expansion: Example 1

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In this video I will show you how to calculate the thermal area expansion of a sheet of aluminum.

[@henryh.448]

If the area increases by 1.00375 times, can we assume the dimensions increase proportionally to sqrt(1.00375)? In other words, 6*1.00187 = 6.01124 m and 4*1.00187 = 4.00749 m. Is this correct? But then what would you do with more weird shapes like triangles and ellipses?

[@enchantedmay8909]

hello sir,shouldn't the percent change is in negative which is -0.375%?since value of original A is smaller than the value of final ?

[@AbrahamHailemichael]

dear sir, can you show us the detail calculation instead of using calculator.

[@MichelvanBiezen]

Original A = 24 Final A = 24.09

[@nicoangelogregorio7494]

Thank youuu Prof.

[@MichelvanBiezen]

You are welcome.

[@NotLegato]

since A = A_0 + 2A_0*alpha*dT and L = L_0 + L_0*alpha*dT... i notice you get *slightly* different results for the length changes depending on the width of the object: is the length change formula only useful for *very* thin objects or what? seems strange...

[@MichelvanBiezen]

The method for finding the change in the area ignores the delta L x delta L term. And yes the answer will therefore be slightly different, but since delta L is very small it doesn't matter.

[@ahmedal-ebrashy3691]

Sir why the the percentage is not negative?

[@MichelvanBiezen]

It is not important if the % is negative or positive since we understand that the object will typically become smaller with smaller temperatures. (Note the absolute value in the equation in order to keep it positive and thus it is the percent change relative to the original size)

[@siamiam]

thank you :)