A glass contains 0.30 kg of water at 70∘C70^\circ\text{C}70∘C. Some time later, the water has cooled to 20∘C20^\circ\text{C}20∘C.
How much thermal energy has been transferred from the water to the surroundings?
(The specific heat capacity of water is 4200 J/(kg⋅∘C)4200\text{ J}/(\text{kg}\cdot^\circ\text{C})4200 J/(kg⋅∘C).)
21 000 J21\,000\text{ J}21000 J
25 200 J25\,200\text{ J}25200 J
63 000 J63\,000\text{ J}63000 J
88 200 J88\,200\text{ J}88200 J
119 exam-style questions on CIE IGCSE Physics 2.2.2a Internal energy and temperature. Each one has a worked solution and a mark scheme showing where the marks go.