They are the very bases of life, no life would exist without cells
When you move your hands, you have kinetic energy. Once your hands collide, that energy has to go somewhere. It turns into heat and sound waves that creates ripples which disturbs the air particle. This is how sound works, a disturbance in air particles.
The correct option is this: WARMER AND LESS DENSE AIR.
Thunderstorm usually occur when a cold dense air converge with a warmer and less dense air. The sun typically heat up the earth surface and make the air on the earth surface to warm up, become less dense and rise up while the colder air above sinks to the earth. This process of convection plays a major role is the formation of thunderstorms.
Height,h= 20m
"gently dropped" means initial velocity, u, =0m/s
Uniform acceleration, g=10m/s²
using the formula v²=u²+2gs
Substituting, v²=0²+2*10*20
v²=400
v=
v=20m/s
Time, t at which is strike the ground
using the formula v=u+at
Substituting, 20=0+10t
20=10t
t=2s
This means that the bank strike the ground with a velocity of 20m/s in 2s.