Internal Enery, heat and work/HELP

[SAT2400]

Homework Statement

There's .1 mole of an ideal gas trapped in a cylinder with a movable piston.
If Pi= Pf= 5000Pa, Vi= .04 m^3, Vf= .08m^3, Q=500J,,,Find W, change in (U), Ti and Tf.

Homework Equations

change in U = Q+W
W= -p change in V

The Attempt at a Solution

W= 200J
change in U = 700J
Ti=
Tf= i don't know how to get Ti and Tf... I am not sure whether 200J and 700J are right either..
PLease help me!
Thank you!

 

[ehild]

You certainly know an equation connecting P, V and T for an ideal gas.

The gas expands, is the work done on the gas positive or negative? Will this work increase or decrase the internal energy?

ehild

 

[SAT2400]

PV=nRT

Could you please explain more in detail? I don't get what you're saying:(

THanks.

 

[ehild]

You know P, V, n for both states of the gas, don't you? Can you calculate the temperatures?

ehild