When you are measuring the length of simple pendulum's moment arm (distance to center), which statement is right. (ppt)

a) measure the distance between the center of mass of the pendulum bob and the pivot of the string.

b) the string doesn't need to be taut

c) pivot and center of mass of bob are same thing

First answer marked as brainiest which is the correct equation describing the first law of thermodynamics? a) when the internal energy of a system changes, it equals the amount of heat added plus the work done. b) when work is done by the piston, it is equal to the heat added plus the change in internal energy of the system. c) when heat is added to the system, it is equal to the amount of work done by the piston plus the change in internal energy of the system.