How much energy is required to raise .. help me please?

Question

A swimming pool, 10.0 m by 4.00 m, is filled to a depth of 2.50 m with water at a temperature of 20.5 deg. C. How much energy is required to raise the temperature of the water to a more comfortable 30.0 deg. C?

Answer 1

Volume water = 10.0 x 4.0 x 2.50 = 100 m^3

=> 100,000 dm^3 = 100,000 L

Assuming density = 1g/mL

Mass water = 100,000,000 g

Q = mass x specific heat x delta T =

= 100.000,000 g x 4.186 J/°Cg x ( 30 - 20.5) =3976700000 J => 3976700 kJ

Answer 2

10.0 M * 4.0 * 2.5 M = 100 Cubic metres water weighs 100 M.T.

100 cubic metres * 1000 = 1,00,000 Kgs.

Temperature difference is 30.0 - 20.50  = 9.5 Degree C

9.5 x 100000 KCal heat shall be added.