The block on the action of two forces, the Force of Friction and the Tangential Weight. Using the Newton's Secound Law, we have:
Using the Velocity Hourly Equation, we get:
Uniting the equations:
Entering the unknowns:

Obs: Approximate results
If you notice any mistake in my english, please let me know, because i am not native.
B.
prokaryotic because prokaryotic cells lack a nucleus and membrane-bound structures.
Answer:Reducing mass i.e. water
Explanation:
Frequency For given mass in glass is given by

where k =stiffness of the glass
m=mass of water in glass
from the above expression we can see that if mass is inversely Proportional to frequency
thus reducing mass we can increase frequency
I would say that there shouldn't be any calls on a plane while in-flight because you never know what someone is calling for. It can lead to a bad situation like 9/11 or any form of terrorism.