The circular clapper on the air side of a dry pipe sprinkler valve has a diameter of 10 in (25cm). what force will be acting on this clapper due to an air pressure of 40psi(3bar)?
correct answer from back of book is: 3141.6lbs
how do i get this answer? show me all the formulas and steps you took to get this answer,

Scout feels ill one day before school. her mother puts a thermometer in her mouth and the temperature begins to climb to 100°f. what is happening between the cooler thermometer and scout's body? a) scout's body is applying a force to the particles in the thermometer. b) kinetic energy is being transferred from her mouth to the thermometer. c) potential energy is being lost by the thermometer and gained by scout's body. d) the potential energy stored in foods is converted to mechanical energy to raise the mercury in the thermometer.