What is the mass of water used to cool the iron car engine?

[studenta]

A 2.50 x 10^2 kg iron car engine contains water as coolant. Suppose the temperature of engine is 35 degree celcius when it shut off and air temperature is 10degree celcius. The heat given off by engine and watering it as they cool to air temperature is 4.4 x10^6 J. What is the mass of water used to cool engine?

 

[gneill]

You must make an attempt at solving the problem before help can offered. What formulas are relevant? What have you tried?

 

[studenta]

You must make an attempt at solving the problem before help can offered. What formulas are relevant? What have you tried?

This is what i did:

Q for iron = mc(tf-ti)
= 2.50 x 10^2 kg x 450 J/kg/°c x (10°c - 35°c)
= -2.813 x 10^6 J

Q for water = 4.4 x10^6 J - 2.813 x 10^6 J
= 1.587 x10^6 J

mass for water = Q / c x (tf-ti)
= 1.587 x10^6 J / 4180 x ( 10°c - 35°c)
= 15.0 kg

Is it right?

 

[gneill]

That looks fine.