A thin aluminum plate has a surface area of 1.500m at 20ºC. What will be its surface area when it is cooled to -20ºC? (Take the linear expansivity of aluminum to be 2.5 x 10-5k-1).
1.503m2
1.500m2
1.498m2
1.497m2
1.490m2
Explanation
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myschool! myschool!! myschool!!! how many times did i call you people. The answer is 1.497m^2...mstcheww
A2= A1(1+(area expansivity×temperature change)
A2=?
A1=1.5
Area expansivity=2× linear expansiviy=2×2.5×10^-5= 5×10^-5
Temperature change= T2-T1= -20-20= -40
Substitute the values
A2= 1.5(1+ (5×10^-5 × -40)
A2=1.5(1+ -0.002)
A2=1.5(0.998)
A2=1.497
i don't understand where you guys are getting 1.497m²..
let's get the change in area back using 1.497m²
¤A = A2 - A1
= 1.497 - 1.5
= - 0.003
now lets use 1.503m³
¤A = 1.503 - 1.5
= 0.003
option D gives - but option A is +
The values in your explanation and the values in your question doesn't correspond.
In your question, the temperature is from 20°C to -20°C, but in your answer, you used -20°C and -20°C . How come?? 🥴
first the surface area given is 1.500m^2
using this the answer should be 1.497m2 so D is correct
-20 -20 = -40
so your change in area will end up being (-ve )
¤A = A2-A1
-0.003=A2 - 1.5
-0.003 + 1.5 = A2
= 1.497m²
