Calculating Gas Pressure in a Piston System with Added Weight

[dragon162]

Homework Statement

Suppose the system is at room temperature, 300 kelvin, and that before we put weights on top of the plunger in the cylinder the pressure inside is 1 atmosphere.

1)If i place a .5kg block on top of the piston, what is the pressure of the gas inside the cylinder?
2)At that pressure what is the volume of the gas?
3)If i want to have L=0cm what should the pressure be?
4)how much mass would we have to pile on top of the piston to achieve that pressure inside the system?

Homework Equations

PV=nRT
Volume of piston is V=L*A

The Attempt at a Solution

Ok I am confused as how to find the pressure of the gas when the block is added to the piston. Since the block is on the piston doesn't it apply a pressure of mg, (.5kg)(9.8)=4.9?

The second part is obvious, just use PV=nRT but I have to find the pressure in part 1 first. As for the other two I don't know how to start them but I am focused on the first part right now.

 

[dragon162]

bumpy bump help please

 

[Redbelly98]

The Attempt at a Solution

Ok I am confused as how to find the pressure of the gas when the block is added to the piston. Since the block is on the piston doesn't it apply a pressure of mg, (.5kg)(9.8)=4.9?

mg would be a force, not a pressure. The block applies a force of mg. To get the pressure, you would need to know the area of the piston's face. Without that information, the problem cannot be solved.