Which of the following statements is true about electric forces? a. electric forces cause objects to only attract each other. b. electric forces cause objects to only repel each other. c. electric forces cause objects to repel or attract each other. d. electric forces have no effect on each other.

An isotope undergoes radioactive decay by emitting radiation that has a –1 charge. what other characteristic does the radiation have?

Dao makes a table to identify the variables used in the equations for centripetal acceleration. what quantities belong in cells x and y?

Arigid tank is divided into two equal parts by a partition. one part of the tank contains 3 kg of compressed liquid water at 400 kpa and 60°c while the other part is evacuated. the partition is now removed, and the water expands to fill the entire tank. determine the entropy change of water during this process, if the final pressure in the tank is 40 kpa. use steam tables.