Forces cause changes in the motion of an object. Newton’s Laws help us to understand and analyse those changes. Unbalanced forces cause changes in speed, shape or direction.

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.

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

Mass added to glider in kg | Total mass in kg | Run 1 | Run 2 | Run 3 | Mean | |
---|---|---|---|---|---|---|

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

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

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

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

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

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

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

For the total mass of each glider, calculate the value of .

For example, 100 g has a mass of 0.1 kg. The value of is = 10 /kg.

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

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

Acceleration is inversely proportional to the mass of the object. This means that a graph of acceleration against 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 glider falling to floor | Objects falling on feet | Use relatively small masses and step back after releasing glider |