An ideal gas in a balloon is kept in thermal equilibrium with its constant-temperature surroundings. how much work is done if the pressure is slowly reduced and the balloon expands to five times its original size?
the balloon initially has a pressure of 815.0 pa and has a volume of 0.70 m^3.

Abird flies directly overhead from where you stand at an altitude of 300.0 m and at a speed horizontal to the ground of 20.0 m/s. the bird has a mass of 2.0 kg. the radius vector to the bird makes an angle \thetaθ with respect to the ground. the radius vector to the bird and its momentum vector lie in the xyxy-plane. what is the bird’s angular momentum about the point where you are standing?