I have 2 problems that i cant do You apply a force of 0.35N up to lift a fork. The resulting acceleration is 0.15m/s2 up. Determine the mass of the fork (the answer is 35g-why?) A hot air balloon has acceleration of 1.10m/s2 down. The mass is 315kg. What is the upward force on the system? The balloonist wished to change acceleration to zero. Determine the mass of the ballast that must be discarded overboard (air resistance is neglected) please help!!