# Volume Expansion

## Homework Statement

a steel tank is 70 litres,full of petrol. If a temperature is change from 20o C to 35o, find the increased volume of petrol that overflows

(βsteel = 950 x 10-6 )
βpetrol = 36 x 10-6 )

Δv=βv0ΔT

## The Attempt at a Solution

I know that both the steel tank and petrol will be increased by the heat and my equation is

change in volume of petrol - change in volume of steel = volume of petrol that overflows
Δvpetrol - Δvsteel = vf

and I got stuck with the volume of the tank :/

kuruman
Homework Helper
Gold Member
I think that you are expected to assume that the tank is full to the brim. Otherwise, you will not be able to do the problem.

I think that you are expected to assume that the tank is full to the brim. Otherwise, you will not be able to do the problem.
yes, in that case

gneill
Mentor
(βsteel = 950 x 10-6 )
βpetrol = 36 x 10-6 )
I think you may have swapped the β values. If there's to be an overflow, shouldn't the oil volume expand more than the steel volume for the same change in temperature?

CWatters
Homework Helper
Gold Member
+1 google suggest the beta values have been swapped. I found 33 for iron and 700ish for various oils.

I think you may have swapped the β values. If there's to be an overflow, shouldn't the oil volume expand more than the steel volume for the same change in temperature?

Oops, yes my mistake ( I can't edit on my phone right now)

I asked my friend, she said the volume of the tank is the same as petrol but why? Or we assume that wall the tank is very thin?

Chestermiller
Mentor
Oops, yes my mistake ( I can't edit on my phone right now)

I asked my friend, she said the volume of the tank is the same as petrol but why? Or we assume that wall the tank is very thin?
Why would the wall thickness of the tank be a factor?

gneill
Mentor
I asked my friend, she said the volume of the tank is the same as petrol but why? Or we assume that wall the tank is very thin?
You can think of it as the tank's fluid capacity (the volume of its interior space). You can imagine the walls of the tank being as thick or thin as you wish so long as its initial capacity matches the given amount of oil.

kuruman