Two small rings each of weight w can slide on a fixed rough horizontal rod. the rings are attached one to each end of a uniform chain of weight 4w and length 4a so that the chain hangs freely from the rings. if the coefficient of friction between each ring and the rod is 1/2, find the distance between the rings when they are in limiting equilibrium. prove that the lowest point of the chain is then at a depth a below the rod.

Aman throws a football straight into the air. as it rises, it slows down. which type of energy is the football gaining?

Which of these is not a possible type of energy transformation? a. electrical energy into light energy b. sound energy into nuclear energy c. potential energy into kinetic energy d. kinetic energy into mechanical energy

Simon is writing a story about an astronaut whose spacecraft has been boarded by space pirates. the astronaut has her lucky penny in her hand behind her back as the space pirates break into the control room. she has just locked the controls so that the ship is accelerating in the direction of the control room’s ceiling. simon wants the astronaut to use the penny to hit a button on the control panel to turn off the lights and escape. the button is located a short distance behind and below the astronaut’s hands. how should simon use the theory of relativity to describe what the astronaut must do in order to hit the button?