Answer:
2587.2 J.
Explanation:
From potential energy,
The work done to lift the chain = potential energy of the chain.
W = mgh............... Equation 1
Where W = work done to lift the chain, m = mass of the chain, g = acceleration due to gravity of the chain, h = height of the chain.
But,
m = m'd............... Equation 2
Where m' = density of the chain, d = length of the chain.
Substitute equation 2 into equation 1
W = m'dgh................ Equation 3
Given: m' = 2 kg/m, d = 12 m, h = 11 m, g = 9.8 m/s²
Substitute into equation 3
W = 2(12)(11)(9.8)
W = 2587.2 J.
Answer:
Part a)

Part b)

Part c)

Part d)

Explanation:
Part a)
As we know that speed of package is same as that of helicopter in horizontal direction
So after time "t" the velocity in x direction will remain constant while in Y direction it will go free fall
So we have



Part b)
Distance from helicopter is same as the distance of free fall
so we will have

Part c)
If helicopter is rising upwards with uniform speed
then final speed of the package after time t is given as


Part d)
distance from helicopter

Answer: 
Explanation:
The mean free path
of an atom is given by the following formula:
(1)
Where:

is the Universal gas constant
is the absolute standard temperature
is the diameter of the helium atom
is the Avogadro's number
absolute standard pressure
Knowing this, let's find
from (1), in order to find the radius
of the helium atom:
(2)
(3)
(4)
If the radius is half the diameter:
(5)
Then:
(6)
(7)
However, we were asked to find this radius in nanometers. Knowing
:
(8)
Finally:
This is the radius of the helium atom in nanometers.