Investigate the effect of varying the force on the acceleration of an object of constant mass

Investigate the effect of varying the mass of an object on the acceleration produced by a constant force.


There are different ways to investigate the effect of varying the force on an object. In this required practical activity, it is important to:

◆  make and record measurements of length, mass and time accurately

◆  measure and observe the effect of force

◆  use appropriate apparatus and methods to measure motion

The diagram shows apparatus that can be used in this investigation. A constant stream of air reduces the friction between the glider and the air track.


1. Position 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 known length (such as 10 cm) and attach it to an air track glider.

2. Connect the glider to a hanging mass by a string the length of the air track passing over the bench pulley. Make sure the air track is level and that 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 masses to the end of the string and calculate weight by using equation

W = m x g.

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 different forces).


Plot a line graph with acceleration on the vertical axis, and force on the horizontal axis. Draw a suitable line of best fit.