Question

How much heat is absorbed by a 2000 kg granite boulder as energy from the sun causes its temperature to change from 10°C to 29°C?

Answer 1

3.002 MJ

Explanation:

Heat absorbed,
`H= m.c. del(theta)`
Where, m= mass,
C= specific heat capacity. Assume `c=790 J/(kg)/K` for granite.
`del(theta)` is the change in temperature.
Hence, `del(theta)=29-10=19K`

(Note: For difference of temperature, Celsius degrees and Kelvin are interchangeable, as the interval for both scales is the same.)

Then we have,
`H=2000*790*19 = 3002000 J = 3.002 MJ`

Answer 2

Apply the equation

`color (red)(Q = mCpDeltaT)`

`color(blue)("Where Q is heat absorbed")`

`color(blue)("Cp is the specific heat")`

`color(blue)(DeltaT "is " t_"final" - t_"initial"`

`color(blue)("m is mass in grams")`

The `Cp` of granite

`Cp` of granite is `"0.79J/g"*C^@`

Convert 2000kg to grams = `2*10^6g`

`2*10^6g xx "0.79J/g"*C^@ xx (29C^@-10C^@) = 30 020 000J`