Scientists study the life history of stars by examining what trait of stars? a. size b. energy output c. color d. all of these

Note: the following questions are unrelated to the balmer series or the martian. refer to your course notes. a sun-sized star will spend most of its lifetime as a: white dwarf b. red giant c. protostar d. main-sequence star

What tightening torque should be used for a hexagonal head screw (not split-bolt) on a 250 kcmil conductor?

As you are trying to move a heavy box of mass m, you realize that it is too heavy for you to lift by yourself. there is no one around to , so you attach an ideal pulley to the box and a massless rope to the ceiling, which you wrap around the pulley. you pull up on the rope to lift the box. use g for the magnitude of the acceleration due to gravity and neglect friction forces. once you have pulled hard enough to start the box moving upward, what is the magnitude f of the upward force you must apply to the rope to start raising the box with constant velocity? express the magnitude of the force in terms of m, the mass of the box.