What is the required practical to investigate the effect of varying force on the acceleration of an object at a constant mass?

1)Place an air track on a bench with a bench pulley at one end and two light gates above the track. Cut an interrupt card to a length (eg 10 cm) and attach it to an air track glider. 2)Connect the glider to a hanging mass by a string that is the length of the air track passing over the bench pulley. Make sure the air track is level & the card will pass through both gates before the mass strikes the floor. 3)Set the data logging software to calculate acceleration. 4)Add 5 × 20 g slotted masses (0.98 N of force) to the end of the string. 5)Release the glider, then record the weight and acceleration. 6)Repeat steps 4 and 5 two more times, and calculate a mean value for the acceleration. 7)Repeat steps 4 to 6, removing one of the slotted masses each time ,giving forces of 0.78 N, 0.59 N, 0.39 N and 0.20 N.