1. Cylinder contains 0.1 mol of ideal gas at a pressure of 2 atm and temperature of 300 K. The volume of the cylinder is 1.25 x 10^-3 m3. When the gas is heated from 300K to 350K, what is the change in internal energy of the gas? --->(I think the equation is Q=delta U + W but I don't know how to proceed from there.) 2. So of all the properties of waves (speed, amplitude, wavelength and frequency) which one is independent of the others? --> Is it amplitude? 3. A train is blowing its whistle at 860Hz while traveling at a speed of 40m/s. The speed of sound is 340 m/s. What is the frequency heard by a stationary observer in front of the train? ---> I used the equation, f'= f (1/1+ or - Vs/V) and I got 769 Hz as the answer but I'd like to confirm with someone whether I am doing it correctly. Thanks!