Calculating Specific Heat Capacity

[struggtofunc]

Homework Statement

A 4.96 kg piece of solid material is heated from 16.7oC to 234oC (3 s.f.) using 725 kJ of energy (3 s.f.).

Assuming an efficiency of 0.342 for the heating process, and that the material does not melt, calculate the specific heat capacity of the material.

m = 4.96 kg
change in T = 217.3 celsius
energy = 725000 J
efficiency = 0.342

Homework Equations

Q = (m)(c)(change in T)

The Attempt at a Solution

c = Q/(m*change in T)

I have calculated Q using .342*725000 = 247950.

I then plugged in these values into the equation and am still getting the wrong answer.

I've also tried dividing 725000/.342 and plugging those values in but it's still incorrect.

What should I be doing in regards to the efficiency?

Thanks!

 

[Chestermiller]

Homework Statement

A 4.96 kg piece of solid material is heated from 16.7oC to 234oC (3 s.f.) using 725 kJ of energy (3 s.f.).

Assuming an efficiency of 0.342 for the heating process, and that the material does not melt, calculate the specific heat capacity of the material.

m = 4.96 kg
change in T = 217.3 celsius
energy = 725000 J
efficiency = 0.342

Homework Equations

Q = (m)(c)(change in T)

The Attempt at a Solution

c = Q/(m*change in T)

I have calculated Q using .342*725000 = 247950.

I then plugged in these values into the equation and am still getting the wrong answer.

I've also tried dividing 725000/.342 and plugging those values in but it's still incorrect.

What should I be doing in regards to the efficiency?

Thanks!

Please show the details of your calculation of c.

 

[struggtofunc]

c = 247950/(4.96*217.3) = 230. 05 J/kg/K

 

[Chestermiller]

c = 247950/(4.96*217.3) = 230. 05 J/kg/K

This looks OK, but isn't it usually reported as kJ/kg/K? Also, shouldn't the significant figures be less?

 

[struggtofunc]

Hi chestermiller,

Yes, I input the answer as 230 J/kg/K because it was what we were told to present it in. It's still showing as incorrect though.

 

[Chestermiller]

Hi chestermiller,

Yes, I input the answer as 230 J/kg/K because it was what we were told to present it in. It's still showing as incorrect though.

I don't know what else to suggest. This answer looks correct.

 

[struggtofunc]

No worries. Thank you very much for your help!