# First law of thermodynamics problem

## Homework Statement

An ideal monoatomic gas is held in a perfectly insulated cylinder fitted with a movable piston. Initial pressure is 110kPa, initial temperature is 280K. By pushing on the piston the pressure increases to 140kPa. Find the final temperature.

## Homework Equations

Q=nCdT (d means delta)

## The Attempt at a Solution

I have thought of using the above eqn but moles is not given and i have thought of using PV=nRT but the volume isn't given either so i dont know how you can solve with two unknown variables. Please help

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you can use the equation P1/T1 = P2/T2 where P1 is initial pressure and T1 is initial Temperature and P2 is final pressure and T2 is final temperature.

Redbelly98
Staff Emeritus
Homework Helper

## Homework Statement

An ideal monoatomic gas is held in a perfectly insulated cylinder fitted with a movable piston. Initial pressure is 110kPa, initial temperature is 280K. By pushing on the piston the pressure increases to 140kPa. Find the final temperature.

## Homework Equations

Q=nCdT (d means delta)

## The Attempt at a Solution

I have thought of using the above eqn but moles is not given and i have thought of using PV=nRT but the volume isn't given either so i dont know how you can solve with two unknown variables. Please help
Welcome to physics forums.
Since the cylinder is insulated, there is no heat added (Q=0) and this is an adiabatic process. What does your textbook or class notes say about adiabatic processes and ideal gases? Hint: there is a relation between P and V involved.

you can use the equation P1/T1 = P2/T2 where P1 is initial pressure and T1 is initial Temperature and P2 is final pressure and T2 is final temperature.
That would be true if the volume were the same. But the volume changes in this problem.