What is the change in internal energy if 70 j of heat is added to a system and the system does 30 j of work on the surroundings?

a. 40 j
b. 100 j
c. -40 j
d. -100 j

Where is the potential energy throughout the loading, cocking, and releasing of the trebuchet?

Assume that two of the electrons at the negative terminal have attached themselves to a nearby neutral atom. there is now a negative ion with a charge -2e at this terminal. what are the electric potential and electric potential energy of the negative ion relative to the electron? the electric potential and the electric potential energy are both twice as much. the electric potential is twice as much and the electric potential energy is the same. the electric potential is the same and the electric potential energy is twice as much. the electric potential and the electric potential energy are both the same. the electric potential is the same and the electric potential energy is increased by the mass ratio of the oxygen ion to the electron. the electric potential is twice as much and the electric potential energy is increased by the mass ratio of the oxygen ion to the electron.

In addition to gravity, what is the other predominant force that affects the motion of a pendulum?