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## Main Question or Discussion Point

I'm trying to determine how much water it takes to raise a car's temperature from -25°C to 0°C. The water is at 10°C.

What I apparently need to have set up is:

-ΔU

-(m

The resultant rearranged equation looking for mass of water gives this:

m

I don't understand how this was done. Also, why are you subtracting Latent heat of fusion x Mass from m

What I apparently need to have set up is:

-ΔU

_{int,water}= ΔU_{int,car}-(m

_{w}c_{w}ΔT_{w}) - m_{w}L_{f,w}= m_{c}c_{c}ΔT_{c}The resultant rearranged equation looking for mass of water gives this:

m

_{w}= -(m_{c}c_{c}ΔT_{c})/c_{w}ΔT_{w}- m_{w}L_{f,w}I don't understand how this was done. Also, why are you subtracting Latent heat of fusion x Mass from m

_{w}c_{w}ΔT_{w}?