The system's tension is 616 N and acceleration is 5.6 
<u>Explanation:</u>
From newton’s second law of motion which state that net force acting on a body is product of mass of a body and acceleration of a body which is given as,

Where,
is net force acting on body
is mass of body
a is acceleration of body
Given values
Table mass (m) = 30 kg
Hanging mass (m) = 40 kg

Put the value for m = hanging mass = 40 kg and
, we get

The tension in the ropes, 
Here, m as hanging mass
T = tension, N or 
m = mass, kg
g = gravitational force, 
a = acceleration, 

On half life is 5370 years; 6 half lives have passed. You just multiply,
5370*6 = 32,220 years
Answer:
Force exerted by the air on the propellers = 46000 - 9200
= 36800 N
Hope this helps!
When light ray pass from air into water, its speed and wavelength change only the frequency of the light doesn't change.
Light travels slower in a medium of higher refractive index. It bends because of this change in speed. The wavelength of light also changes in order to maintain the constant frequency.