Answer:
Momentum, p = 7.2 g-m/s
Explanation:
It is given that,
The momentum of an object is 
We need to express momentum in any equivalent units. There can be many solutions of this problem. Some of the units of mass are gram, milligram etc. units of length are meters, mm etc.
Since, 1 kg = 1000 gram
So, 
Therefore, the momentum of the object is 7.2 g-m/s. Hence, this is the required solution.
We can take as positive direction the direction of the train, and as negative direction the direction of the girl. The speed of the train relative to the girl will be given by the difference between the two velocities:

which means
Answer: The statement first and the fourth statement are true.
Explanation:
According to Newton's gravitational law, every particle in the universe attracts every other particle with the force of attraction between the masses is directly proportional to the product of the masses and inversely proportional to the square of the distance between them.
As we move to higher altitude, the force of gravity on use decreases because the force of gravity is inversely proportional to the distance.
If the masses of the two objects are more then there will be greater force of gravity between them.
Therefore, the statement first and the fourth statement are true.
Answer:
The value is 
Explanation:
From the question we are told that
The Coulomb constant is 
The charge on the electron/proton is 
The mass of proton 
The mass of electron is 
Generally for the electron to be held up by the force gravity
Then
Electric force on the electron = The gravitational Force
i.e



