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,
Mass will remain unchanged, always. His weight, which is the gravitational force acting on that mass will be less in this case.
Answer:
A half-life is the time required for one half of the nuclei in a radio- active isotope to decay.
Explanation:
A radio-active isotope is an isotope which undergoes radioactive decay.
Radioactive decay is a spontaneous process in which the nucleus of an atom changes its state (turning into a different nucleus, or de-exciting), emitting radiation, which can be of three different types: alpha, beta or gamma.
The half-life of a radio-active isotope is the time required for half of the nuclei of the initial sample to decay.
The law of radio-active decay can be expressed as follows:
where
N(t) is the number of undecayed nuclei left at time t
N0 is the initial number of nuclei
t is the time
is the half-life
We see that when 
(that means, when 1 half-life has passed), the number of undecayed nuclei left is
So, half of the initial nuclei.
D is the amount of space object takes up
