03 Trying Hard to Pull Differently

03 Trying Hard to Pull Differently#

Aim#

To show (again) the validity of Newton’s third law.

Subjects#

  • 1H10 (Action and Reaction)

Diagram#

../../../../../_images/figure_029.png

Fig. 81 .#

Equipment#

  • Two force sensors.

  • Rubber band.

  • Data acquisition via Science Workshop.

  • Projector to project on the monitor screen

  • Trying hard to pull differently

Presentation#

On the monitor, two graphs are presented for each force sensor. The software is set in such a way that one of the sensors presents \(-F\).

Two demonstrators take each of the sensors. They start both pulling randomly. The display shows clearly that whatever they do, both force sensors measure the same force: \(-F\) and \(-F\) (see Figure 82).

../../../../../_images/figure_122.png

Fig. 82 .#

Also, when one of the demonstrators holds his force sensor without moving it, while the other demonstrator moves again randomly, then both force sensors register an equal \(F\) and \(-F\). The registration does not reveal which of the two demonstrators is not moving his sensor.

Explanation#

Again, the validity of Newton’s third law is shown.

Sources#

  • Giancoli, D.G., Physics for scientists and engineers with modern physics, pag. 82

  • Mansfield, M and O’Sullivan, C., Understanding physics, pag. 119

  • McComb,W.D., Dynamics and Relativity, pag. 1

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