To develop the problem it is necessary to apply two concepts, the first is related to the calculation of average data and the second is the Boltzmann distribution.
Boltzmann distribution is a probability distribution or probability measure that gives the probability that a system will be in a certain state as a function of that state's energy and the temperature of the system. It is given by

Where,
energy of that state
k = Boltzmann's constant
T = Temperature
With our values we have that
T= 250K




To make the calculations easier we can assume that the temperature and Boltzmann constant can be summarized as



Therefore the average energy would be,

Replacing with our values we have


Therefore the average internal energy is 
I think it is B. Sorry if I’m wrong
Answer:
1.) U = 39.2 m/s
2.) t = 4s
Explanation: Given that the
height H = 78.4m
The projectile is fired vertically upwards under the acceleration due to gravity g = 9.8 m/s^2
Let's assume that the maximum height = 78.4m. And at maximum height, final velocity V = 0
Velocity of projections can be achieved by using the formula
V^2 = U^2 - 2gH
g will be negative as the object is moving against the gravity
0 = U^2 - 2 × 9.8 × 78.4
U^2 = 1536.64
U = sqrt( 1536.64 )
U = 39.2 m/s
The time it takes to reach its highest point can be calculated by using the formula;
V = U - gt
Where V = 0
Substitute U and t into the formula
0 = 39.2 - 9.8 × t
9.8t = 39.2
t = 39.2/9.8
t = 4 seconds.
Answer:
A) Impulse is the same for both the objects
B) The higher is the speed, the greater will be the height.
Explanation:
Part a)
The time of interaction of the two bodies i.e the hanging mass and the stick is same. Thus, force caused by dart on the block = force caused by block on the dart. Hence, impulse is the same for both the objects.
Part B
The energy will be conserved in the entire reaction process
Hence, Kinetic energy = potential energy
0.5Mv^2 = gh(md+mb)
H is directly proportional to the square of speed.
Hence, the higher is the speed, the greater will be the height.