Force and acceleration experiment
Investigate the effect of varying the force on the acceleration of an object of constant mass
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.
Aim of the experiment
To investigate the effect of varying the force on the acceleration of an object.
Method
- 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.
- 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.
- Set the data logging software to calculate acceleration.
- Add 5 脳 20 g slotted masses (0.98 N of force) to the end of the string.
- Release the glider, then record the weight and acceleration.
- Repeat steps 4 and 5 two more times, and calculate a mean value for the acceleration.
- 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.
Results
It is important to record results in a suitable table, like the one below, which shows a set of example results:
| Force (N) | Run 1 acceleration (m/s)2 | Run 2 acceleration (m/s)2 | Run 3 acceleration (m/s)2 | Mean acceleration (m/s)2 |
| 0.98 | 0.22 | 0.27 | 0.37 | 0.29 |
| 0.78 | 0.20 | 0.29 | 0.21 | 0.23 |
| 0.59 | 0.26 | 0.11 | 0.17 | 0.18 |
| 0.39 | 0.21 | 0.10 | 0.05 | 0.12 |
| 0.20 | 0.04 | 0.06 | 0.11 | 0.07 |
| Force (N) | 0.98 |
|---|---|
| Run 1 acceleration (m/s)2 | 0.22 |
| Run 2 acceleration (m/s)2 | 0.27 |
| Run 3 acceleration (m/s)2 | 0.37 |
| Mean acceleration (m/s)2 | 0.29 |
| Force (N) | 0.78 |
|---|---|
| Run 1 acceleration (m/s)2 | 0.20 |
| Run 2 acceleration (m/s)2 | 0.29 |
| Run 3 acceleration (m/s)2 | 0.21 |
| Mean acceleration (m/s)2 | 0.23 |
| Force (N) | 0.59 |
|---|---|
| Run 1 acceleration (m/s)2 | 0.26 |
| Run 2 acceleration (m/s)2 | 0.11 |
| Run 3 acceleration (m/s)2 | 0.17 |
| Mean acceleration (m/s)2 | 0.18 |
| Force (N) | 0.39 |
|---|---|
| Run 1 acceleration (m/s)2 | 0.21 |
| Run 2 acceleration (m/s)2 | 0.10 |
| Run 3 acceleration (m/s)2 | 0.05 |
| Mean acceleration (m/s)2 | 0.12 |
| Force (N) | 0.20 |
|---|---|
| Run 1 acceleration (m/s)2 | 0.04 |
| Run 2 acceleration (m/s)2 | 0.06 |
| Run 3 acceleration (m/s)2 | 0.11 |
| Mean acceleration (m/s)2 | 0.07 |
Analysis
1. Plot a line graph with acceleration on the vertical axis, and force on the horizontal axis. Draw a suitable line of best fit.
2. Describe what the results show about the effect of increasing the force on the acceleration of the object.
Evaluation
Acceleration is directly proportional to the force exerted on the object. It is important to consider to what extent the results show this relationship. For example, do all the points lie on a straight line passing through the origin, or are there any A result which does not agree with other results in the data set. For example, a result which lies well off the line of best fit.?
Hazards and control measures
| Hazard | Consequence | Control measures |
| Electrical appliance | 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. Step back after releasing glider |
| Hazard | Electrical appliance |
|---|---|
| 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. Step back after releasing glider |