Gravity decreases with the square of the distance, so the new force is (20)/(2*2) = 5N.
Answer:
6.5 x 10^32 eV
Explanation:
mass of particle, mo = 1 g = 0.001 kg
velocity of particle, v = half of velocity of light = c / 2
c = 3 x 10^8 m/s
Energy associated to the particle
E = γ mo c^2





Convert Joule into eV
1 eV = 1.6 x 10^-19 J
So, 
The gas is in a rigid container: this means that its volume remains constant. Therefore, we can use Gay-Lussac law, which states that for a gas at constant volume, the pressure is directly proportional to the temperature. The law can be written as follows:

Where P1=5 atm is the initial pressure, T1=254.5 K is the initial temperature, P2 is the new pressure and T2=101.8 K is the new temperature. Re-arranging the equation and using the data of the problem, we can find P2:

So, the new pressure is 2 atm.