Required practical

Investigate the relationship between the force, mass and acceleration by varying the masses added to trolleys

More than one method could be used to investigate the relationship between the force, mass and acceleration. This method will vary the masses added to trolleys.

Aim of the experiment

To investigate the relationship between the force, mass and acceleration by varying the masses added to trolleys.


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

There is an experiment set up, with equipment on top of a table - a vacuum cleaner on blow, a glider and card, light gates, string, bench pulley, weight stack.
  1. Cut an interrupt card to a known length (such as 10 cm) and attach it to an air track glider.
  2. Set up the equipment as shown in the diagram. Make sure that the air track is level, and that the card will pass through both gates before the masses strike the floor.
  3. Set the data logging software to calculate acceleration.
  4. Use scales to measure the total mass of the glider, string and weight stack. Record this value.
  5. Attach the full weight stack (6 x 10g masses) to the end of the string.
  6. Make sure the glider is in position and switch on the air blower. The glider should accelerate.
  7. Remove one weight and attach it to the glider using blu-tack. This will keep the total mass constant. (The weight stack is being accelerated too.)
  8. Repeat steps 6-7 removing one weight from the stack each time. Remember to attach each weight to the glider as it is removed from the weight stack.


Record the results in a suitable table, similar to the example results below:

Number of weights on stackForce in NAcceleration in m/s² - Run 1Acceleration in m/s² - Run 2Acceleration in m/s² - Run 3Acceleration in m/s² - Mean


A scatter graph plotting Force against Acceleration. There is a line of best fit through the points.

  1. Plot a scatter graph with force on the vertical axis, and acceleration on the horizontal axis. Draw a suitable line of best fit.
  2. Describe what the results show about the effect of increasing the force which is accelerating the object.
  3. Extension: calculate the gradient of your graph and compare this to the to total mass of the glider and weight stack measured in step 4 above.


Acceleration is direcly proportional to the force applied to the object. This means that a graph of force against acceleration should produce a straight line that passes through the origin.

To what extent do your results show this relationship? For example, do all your points lie on a straight line passing through the origin, or are there any anomalous points?

HazardConsequenceControl measures
Electrical appliance (air blower)Electrical fault - fire/shock Check mains cable and plug are not broken or wiring exposed before use
Masses and/or glider falling to floorObjects falling on feet - bruise/fractureUse relatively small masses and step back after releasing glider