Required practical - investigating force, mass and acceleration
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.
Method
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.
- Cut an interrupt card to a known length (such as 10 cm) and attach it to an air track glider.
- 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.
- Set the data logging software to calculate acceleration.
- Use scales to measure the total mass of the glider, string and weight stack. Record this value.
- Attach the full weight stack (6 x 10g masses) to the end of the string.
- Make sure the glider is in position and switch on the air blower. The glider should accelerate.
- 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.)
- 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.
Results
Record the results in a suitable table, similar to the example results below:
| Number of weights on stack | Force in N | Acceleration in m/s虏 - Run 1 | Acceleration in m/s虏 - Run 2 | Acceleration in m/s虏 - Run 3 | Acceleration in m/s虏 - Mean |
| 6 | 0.6 | 2.90 | 2.95 | 3.05 | 2.97 |
| 5 | 0.5 | 2.21 | 2.36 | 2.26 | 2.28 |
| 4 | 0.4 | 1.93 | 1.78 | 1.83 | 1.85 |
| 3 | 0.3 | 1.65 | 1.54 | 1.49 | 1.56 |
| 2 | 0.2 | 1.32 | 1.27 | 1.42 | 1.34 |
| 1 | 0.1 | 1.16 | 1.11 | 1.26 | 1.18 |
| Number of weights on stack | 6 |
|---|---|
| Force in N | 0.6 |
| Acceleration in m/s虏 - Run 1 | 2.90 |
| Acceleration in m/s虏 - Run 2 | 2.95 |
| Acceleration in m/s虏 - Run 3 | 3.05 |
| Acceleration in m/s虏 - Mean | 2.97 |
| Number of weights on stack | 5 |
|---|---|
| Force in N | 0.5 |
| Acceleration in m/s虏 - Run 1 | 2.21 |
| Acceleration in m/s虏 - Run 2 | 2.36 |
| Acceleration in m/s虏 - Run 3 | 2.26 |
| Acceleration in m/s虏 - Mean | 2.28 |
| Number of weights on stack | 4 |
|---|---|
| Force in N | 0.4 |
| Acceleration in m/s虏 - Run 1 | 1.93 |
| Acceleration in m/s虏 - Run 2 | 1.78 |
| Acceleration in m/s虏 - Run 3 | 1.83 |
| Acceleration in m/s虏 - Mean | 1.85 |
| Number of weights on stack | 3 |
|---|---|
| Force in N | 0.3 |
| Acceleration in m/s虏 - Run 1 | 1.65 |
| Acceleration in m/s虏 - Run 2 | 1.54 |
| Acceleration in m/s虏 - Run 3 | 1.49 |
| Acceleration in m/s虏 - Mean | 1.56 |
| Number of weights on stack | 2 |
|---|---|
| Force in N | 0.2 |
| Acceleration in m/s虏 - Run 1 | 1.32 |
| Acceleration in m/s虏 - Run 2 | 1.27 |
| Acceleration in m/s虏 - Run 3 | 1.42 |
| Acceleration in m/s虏 - Mean | 1.34 |
| Number of weights on stack | 1 |
|---|---|
| Force in N | 0.1 |
| Acceleration in m/s虏 - Run 1 | 1.16 |
| Acceleration in m/s虏 - Run 2 | 1.11 |
| Acceleration in m/s虏 - Run 3 | 1.26 |
| Acceleration in m/s虏 - Mean | 1.18 |
Analysis
- Plot a scatter graph with force on the vertical axis, and acceleration on the horizontal axis. Draw a suitable line of best fit.
- Describe what the results show about the effect of increasing the force which is accelerating the object.
- 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.
Evaluation
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?
| Hazard | Consequence | Control 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 floor | Objects falling on feet - bruise/fracture | Use relatively small masses and step back after releasing glider |
| Hazard | Electrical appliance (air blower) |
|---|---|
| Consequence | Electrical fault - fire/shock |
| Control measures | Check mains cable and plug are not broken or wiring exposed before use |
| Hazard | Masses and/or glider falling to floor |
|---|---|
| Consequence | Objects falling on feet - bruise/fracture |
| Control measures | Use relatively small masses and step back after releasing glider |