Evaluate the following without the use of a calculator a) 2 sin 150 cos 15 °
b) cos? 15° - sin 15
c) cos? 15° +sin? 15°​

If gases like carbon dioxide and methane make up less than 1% of the total atmosphere, why is it important for scientists to monitor changes in percentages of these gases?

What can you increase the strength of an electromagnet by

(a) if the pressure in gas is doubled while its volume is held constant, by what factor do (i) vrms and (ii) change? (b) is it possible to boil water at room temperature (20oc) without heating it? explain.