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 
Answer:
e) A changing magnetic field produces an electric field.
Explanation:
Ok, we start with a magnetic field and let's study how it affects the motion of a single electron. As the magnetic field changes, it will cause an electromotive force, that moves the electron, and because now we have a moving electron, now we will have an electric field. (Such that the direction of the electromotive force opposes the direction in which the magnetic field changes). This also can be deduced if we look at the third Maxwell's equation:
dE/dx = -dB/dt
This says that the spatial change in an electric field depends on how the magnetic field changes as time pass.
Then the correct option is e) A changing magnetic field produces an electric field.
Answer:
Please see below as the answers are self-explanatory.
Explanation:
1) The resultant force is along the line that joins both charges or both masses (assuming both objects can be represented as points)
2) Both type of forces obey Newton's 3rd law.
3) Both are proportional to the product of the property that is affected by the force (charges and masses)
4) Both obey an inverse - square law (consequence of our universe being three-dimensional)
1) Main difference, is that while the gravitational force is always attractive, the electrostatic force can be attractive or repulsive, as there are two types of charges, which attract each other being of different type, and repel each other if they are of the same type.
2) It is possible, artificially, to block the influence of the electrostatic force, shielding a room, for instance, which is not possible for the gravitational force.
Answer:
The force due to friction is generally independent of the contact area between the two surfaces. This means that even if you have two heavy objects of the same mass, where one is half as long and twice as high as the other one, they still experience the same frictional force when you drag them over the ground.
Explanation:
Independent