In which of the situations listed below is energy being transferred as heat to the system in order for the system to do work? in which situa tion is work being done on the system in order for energy to be trans- ferred from the system as heat? a. two sticks are rubbed together to start a fire. b. a firecracker explodes. c. a red-hot iron bar is set aside to cool.

The safe load, l, of a wooden beam of width w, height h, and length l, supported at both ends, varies directly as the product of the width and the square of the height, and inversely as the length. a wooden beam 4 inches wide, 9 inches high, and 240 inches long can hold a load of 6810 pounds. what load would a beam 3 inches wide, 8 inches high, and 144 inches long, of the same material, support? (round off your answer to the nearest integer.)