A 5.0-kg mass sits on the floor of an elevator that has a downward acceleration of 1.0 m/s2. On top of the 5.0-kg mass is an object of unknown mass. The force of the elevator on the 5.0-kg mass is 80 N up. Determine the unknown mass.
◦ 3.3 kg
◦ 2.4 kg
◦ 1.6 kg
◦ 4.1 kg
◦ 5.0 kg