Science Methods II: Week 4

 





This week in lab, we continued our discussion in supporting play that is fun and not dangerous. We talked about swings this week, which centered around pendulums. We read through a scenario about what some students thought might change the swinging speed of a pendulum, would adding more weight cause the speed to stay the same or speed up? My partner and I had the hypothesis that it would speed up because there would be more weight pulling it to each side. Then, we launched our investigation which showed us that the number of swings stayed the same even when we added more weight. Changing the length of the string, however, did change the number of swings we got in 15 seconds. 

In lecture, we talked more about our lab investigations and about why rider weight does not change the period of a swing because the more mass, the harder gravity pulls, but also more mass is harder to accelerate so these forces cancel out and the period stays the same. Then, we talked about "the energy lens on motion", including that energy is never created or destroyed, energy is transferred from one system to another, and it manifests in several ways including light, heat, movement, and electricity.  In our pendulums, there is the same amount of energy in the system the whole time, it just changes between kinetic and potential energy as it swings back and forth (potential at the top and kinetic at the bottom). 

In this week's reading, "Pendulums and the Energy Lens on Motion", 

I learned: that pendulums allowed the demonstration that Earth rotates on an axis, because after a certain amount of time, a pendulum will knock down all of the pins in a circle due to the spin of the Earth changing its swinging path slowly. 

I found helpful: a pendulum has potential energy at the top of its swing, and kinetic (or "moving") energy at the bottom of its swing. The bottom of the swing has the most kinetic energy which is why wrecking balls smash into things at the bottom of the swing. 

I need more information on: why the weight of the end of a pendulum does not change its speed/number of swings in a period of time, even when the weights can be drastically different. 

I have questions/concerns/comments about: How does a pendulum clock not lose its energy to friction and eventually stop swinging with the seconds?

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