Heat flow, equilibrium and conduction
Answers are for parents and teachers.
1
A cup of tea at 80 °C is left in a 22 °C room. Describe what happens to the tea’s temperature and why.
It falls until it reaches about 22 °C, because heat flows from the tea to the cooler room until equilibrium.
2
Mix 200 g at 10 °C with 200 g at 50 °C. Give the final temperature and show your working.
(10 + 50) ÷ 2 = 30 °C.
3
Explain conduction using the words particles, vibrate and neighbours.
Particles at the hot end vibrate harder and bump their neighbours, passing energy along while staying in place.
4
List three insulators used at home and say what each is for.
Answers differ: for example plastic pan handles, wool blankets, hollow bricks.
5
Find the mistake: “Metal is colder than wood.”
They are at the same room temperature; metal only feels colder because it conducts heat from the hand faster.