Falling objects eventually reach terminal velocity – where their resultant force is zero. Stopping distances depend on speed, mass, road surface and reaction time.

Part of

There are different ways to investigate this.

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

The same apparatus and method can be used as in the investigation on the previous page. However, this time use 100 g (0.98 N) of force for every run, but add increasing numbers of slotted masses to the glider. Preliminary experiments may need to be carried out to find a suitable range of masses to add. Record the total mass of the glider and hanging masses combined.

Mass added to glider (kg) | Total mass (kg) | Acceleration run 1 (m/s^{2}) | Acceleration run 2 (m/s^{2}) | Acceleration run 3 (m/s^{2}) | Mean | |
---|---|---|---|---|---|---|

0.0 | 0.33 | 3.03 | 2.90 | 2.95 | 3.05 | 2.97 |

0.1 | 0.43 | 2.33 | 2.21 | 2.36 | 2.26 | 2.28 |

0.2 | 0.53 | 1.89 | 1.93 | 1.78 | 1.83 | 1.85 |

0.3 | 0.63 | 1.59 | 1.65 | 1.54 | 1.49 | 1.56 |

0.4 | 0.73 | 1.37 | 1.32 | 1.27 | 1.42 | 1.34 |

0.5 | 0.83 | 1.20 | 1.16 | 1.11 | 1.26 | 1.18 |

0.6 | 0.93 | 1.08 | 1.13 | 1.03 | 0.98 | 1.05 |

1. For the total mass of each glider, calculate the value of 1/mass. For example, 100 g has a mass of 0.1 kg. The value of 1/mass is 1/0.1 = 10 /kg.

2. Plot a line graph with acceleration on the vertical axis, and 1/mass on the horizontal axis. Draw a suitable line of best fit.

3. Describe what the results show about the effect of decreasing the mass (increasing the value of 1/mass) of the object on its acceleration.

Acceleration is inversely proportional to the mass of the object. This means that a graph of acceleration against 1/mass 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 | 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 |