I think it will be 'heat' because it doesn't change - only your material changes.
Answer: This was curious, because during so-called REM sleep (rapid eye movement), our muscles are usually paralysed. Researchers realised that inducing a similar state in animals could allow them to probe how they dream.
Explanation:
A free-trade zone is by definition “a place where trade is left to happen without tariffs(tax on imports/exports), quotas, or other restrictions”. An example of a free-trade zone is the European Union. There are no tariffs, quotas, or other restrictions placed on trading within the EU countries (they even share a currency). This allows for them to place products at a cheaper price for good quality and still get enough money to grow wealth within the different countries.
Convection currents are vertical circular movements of fluids that transfer energy due to changes in density.
