## College Physics (4th Edition)

(a) The total mass of Fernando and the dictionary is 54 kg. We can find the total weight: $weight = (54~kg)(9.80~m/s^2) = 529.2~N$ The system of the dictionary and Fernando push down on the table with a weight of 529.2 N. By Newton's third law, the normal force exerted by the table on the dictionary is 529.2 N. (b) We can find the weight of Fernando pushing down on the dictionary: $weight = (52~kg)(9.80~m/s^2) = 509.6~N$ By Newton's third law, the normal force exerted by the dictionary on Fernando is 509.6 N. (c) Since the table is not touching Fernando directly, there is no normal exerted by the table on Fernando.