1200 times 20 times 9.6=24000j
Answer:

Explanation:
Given that:
- area of concrete slab,

- thickness of the layer of air,

- temperature difference between the air and the concrete,

We have:
- thermal conductivity of air at S.T.P.,

<u>Now, according to Fourier's Law of conduction:</u>

putting the respective values:


Answer: Objects
Sink in water: Coins, Marbles and rocks
Float in water: Wood, sponges and apples
Explanation: