PHYS 221 SI Worksheet

1. A gas in a cylinder is held at a constant pressure of 2.30E5 Pa and is cooled and compressed from 1.70 m^3 to 1.20 m^3. The internal energy of the gas decreases by 1.40E5 J. (a) Find the work done by the gas. (b) Find the absolute value |Q| of the heat flow into or out of the gas, and state the direction of the heat flow. (c) Does it matter whether the gas is ideal? Why or why not?

2. A system is taken from state a to state b along the three paths shown on the board. (a) Along which path is the work done by the system the greatest? The least? (b) Along which path is the absolute value |Q| of the heat transfer the greatest? For this path, is heat absorbed or liberated from the system?

3. Three moles of an ideal gas are taken around the cycle abc. For this gas, Cp = 29.12 J/mol·K. Process cb is adiabatic. The temperatures of the gas in states a, b, and c are Ta = 300 K, Tb = 600 K, and Tc = 492 K. Calculate the total work for the cycle.

4. A spot on a wheel is moving in uniform circular motion. The circle has a radius of 3 cm and an angular velocity of 40 rad/s. (a) What is the tangential velocity (m/s) of the spot at any point in its motion? (b) What is the period (s) of the circular motion? (c) What is the frequency (Hz) of the circular motion? (d) If I looked at a different spot just 1 cm from the center of the wheel, what would I observe its angular velocity to be?

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