All step answer electrical principal

What is the heat treatment of metals? what is the benefit of it? why and how it's useful? answer in details, do not write by hand.

For a gate width of 2 m into the paper, determine the force required to hold the gate abc at its location.

Abarometer contains mercury with a density of 13600 kg/m3. atmospheric conditions are 95.8 kpa and 20 °c at 20 °c, the vapor pressure of the mercury is 0.000173 kpa. the column of mercury will rise to a height of most nearly. select one: a)- 0.38 m b)- 0.82 m c)- 0.48 m d)- 0.72 m