An 8.50 kg point mass and a 13.0 kg point mass are held in place 50.0 cm apart. A particle of mass mm is released from a point between the two masses 18.0 cmcm from the 8.50 kg mass along the line connecting the two fixed masses. Required:
Find the magnitude of the acceleration of the particle.

The drag force, fd, imposed by the surrounding air on a vehicle moving with velocity v is given by fd = cdaρv 2/2 where cd is a constant called the drag coefficient, a is the projected frontal area of the vehicle, and ρ is the air density. an automobile is moving at v = 80 kilometers per hour with cd = 0.28, a = 2.3 m2, and ρ = 1.2 kg/m3.