The diagram shows the temperature-time graph for hot water that is cooling in an insulated beaker. The curve starts at 80∘C80^\circ\text{C}80∘C at 0 hours0\text{ hours}0 hours, decreases gradually, and levels off to a horizontal line at 20∘C20^\circ\text{C}20∘C at about 2.5 hours2.5\text{ hours}2.5 hours.
The insulation is now removed from the beaker. The same volume of hot water, at the same initial temperature of 80∘C80^\circ\text{C}80∘C, is put into the uninsulated beaker in the same room as before.
Which of the following describes the new temperature-time graph for the water as it cools?
The curve falls more steeply than the original and levels off at 20∘C20^\circ\text{C}20∘C.
The curve falls less steeply than the original and levels off at 20∘C20^\circ\text{C}20∘C.
The curve falls more steeply than the original and levels off at 40∘C40^\circ\text{C}40∘C.
The curve falls less steeply than the original and levels off at 40∘C40^\circ\text{C}40∘C.
62 exam-style questions on CIE IGCSE Physics 2.3.4 Consequences of thermal energy transfer. Each one has a worked solution and a mark scheme showing where the marks go.