Which of these is considered a contact force? * 1 point
the force between two magnets
the gravitational pull of a planet
the friction between an object and air
the force between two charged particles

Alfred pushes on a heavy box, but cannot move it. the box has a lot of inertia motion friction gravity

Oxygen undergoes an isentropic expansion from 120 degree c and 280 kpa absolute to 140 kpa absolute. determine the final temperature of the oxygen and the amount of work per kg of o_2 produced in the process if it is adiabatic.

Imagine you are standing in the antarctic during the southern hemisphere summer. the sky is clear and blue. there are no clouds in the sky. your shadow is cast on the icy ground. what is the color of the shadow?