C is not mechanical weathering. It is chemical weathering.
Answer:
Force on superball will be 
Explanation:
We have given mass of superball m = 52 gram = 0.052 kg
Velocity change from 20 m/sec downward to 14 m/sec upward
Let downward velocity is positive then upward velocity is negative
So downward velocity is + 20 m/sec and upward velocity is -14 m/sec
Time is given as 1800 sec
We know that acceleration is rate of change of velocity
So 
According to newton second law
Force = ma = 0.052×0.0188 
There all diffrent speeds
Answer : The final pressure of the system in atm is, 3.64 atm
Explanation :
Boyle's Law : It is defined as the pressure of the gas is inversely proportional to the volume of the gas at constant temperature and number of moles.

or,

where,
= first pressure = 8.19 atm
= second pressure = 2.65 atm
= first volume = 2.14 L
= second volume = 9.84 L
= final pressure = ?
= final volume = 2.14 L + 9.84 L = 11.98 L
Now put all the given values in the above equation, we get:


Therefore, the final pressure of the system in atm is, 3.64 atm