Why does the liquid thermometer work?

Which is not a source of noise pollution? a)airplanes b)acid rain c)machines d)cars

When you jump from an elevated position you usually bend your knees upon reaching the ground. by doing this, you make the time of the impact about 10 times as great as for a stiff-legged landing. in this way the average force your body experiences is a) less than 1/10 as great. b) more than 1/10 as great. c) about 1/10 as great.d) about 10 times as great.

Which accurately compares concave and convex lenses?