relationship forced vibration and natural vibration-ogawa · forced vibration and natural vibration...
TRANSCRIPT
RELATIONSHIP FORCED VIBRATION AND NATURAL VIBRATION
Koshi high school Hiroya Ogawa
Satoki Yoshida
Motivation・Purpose
The earth quake of East Japan made Buildings broken. ↓ We decided to think the relationship between moving of object and forced vibration.
Important terms of our experiment
The vibration caused in an object by the power periodically received from an outside source.
The natural vibration caused, when the object freely move.
Important terms of our experiment
The phenomenon that sounds stress periodically change when two sounds having different frequency mix.
Important terms of our experiment
The phenomenon that the swing of the pendulum become larger when moving object received power matching natural peculiar frequency.
Object of this experiment
We applied forced vibration to the pendulum and checked the cycle and swing of beat. ↓ We checked the relationship between them and the cycle of force vibration.
Tools used for our experiment・A vibration device made of LEGO MIND STORM
・A pendulum consisting of a light thread and suitable ball
Tools used for our experiment
・A sensor to measure the distance (PC software:Date studio)
・Stopwatch
Experimental method
Ⅰ
Experimental methodⅠ
T=2.48 The cycle of the vibration device is 2.48s
Experimental method
Ⅱ Ⅲ
Experimental methodⅡ Ⅲ
1.53m
Experimental method
Ⅳ
Experimental methodⅣ
Regular intervals
7.5mm
Experimental methodⅤ
Experimental methodⅤ
1.43m
1.33m
1.23m
1.13m
Experimental method
Ⅵ|f₁
-f₂|
When the pendulum is 1.53m
Max of swing 0.195 m
When the pendulum is 1.43m Max of swing 0.134 m The beat frequency Calculated 69.5 s Real 41 s
When the pendulum is 1.33m Max of swing 0.121 m The beat frequency Calculated 33.6 s Real 38 s
When the pendulum is 1.23m
Max of swing 0.053 m The beat frequency Calculated 21.3 s Real 21 s
When the pendulum is 1.13m
Max of swing 0.038 m The beat frequency Calculated 15.0 s Real 16 s
The whole result of our experimentSwing was getting smaller. Beat frequency was getting bigger. Cycle of pendulum was getting smaller.
However… The length of pendulum which is near 1.53m, difference of the real score and calculated score was getting bigger.
↓ This reasons
The consideration of our experimentTo make pendulum do resonate,
We have to consider other powers from outside so as not to let them affect the experiment.
今後の課題
change
This experiment
Future research
Studying the way of making strong buildings
Or
Searching condition which can stand vibration