An insulated piston-cylinder device initially contains 300 l of air at 120 kpa and 17°c. the
air is now heated for 15 minutes by a 200-w resistance heater placed inside the cylinder.
the pressure of the air is maintained constant during this process. determine the entropy
change of the air assuming (15 points)
a. constant specific heats
b. variable specific heats

The period of a pendulum varies directly as the square root of the length of the pendulum and inversely as the square root of the acceleration due to gravity. find the period when the length is 144 cm and the acceleration due to gravity is 980 cm per second squared, if the period is 7pi seconds when the length is 289 cm and the acceleration due to gravity is 980 cm per second squared.

Estimate the change in the gibbs energy and molar gibbs energy of 1.0dm3 of octane when the pressure acting on it is increased from 1.0 atm to 100 atm. the mass density of octane is 0.703 g cm−3

What was the first instrument to ever record an earthquake?