The piston of a machine exerts a constant force on a ball as it moves horizontally through a distance of 15 cm. You use a motion detector to measure the speed of five different balls as they come off the piston; the data are shown below. Use theory to find two quantities that, when graphed, should give a straight line. Then use the graph to find the size of the piston’s force.

Mass (g)                Speed (m/s)

200..............................9.4

400..............................6.3

600..............................5.2

800..............................4.9

1000............................4.0