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.

You have two photos of a person walking. one shows the person at the corner of third and main streets, the other shows the person at the corner of tenth and main streets. there are lampposts at every corner in this town, and the first picture shows it to be 10: 32: 00 exactly. the second picture shows it to be 10: 49: 30. you know three facts: (1) all of the clocks are synchronized; (2) there are exactly 12 equal-sized blocks per kilometer in this town; and (3) the streets that cross main in this area are numbered consecutively, with no interruptions. what is the person’s average speed in kilometers per hour?