A Study on the Mechanism of a Scientific Toy “Girigiri-Garigari”

Abstract

“Girigiri-Garigari” is the Japanese name of a scientific toy which consists of a square rod and a propeller. The wooden rod has several notches along its long edge, and the propeller is loosely attached to one end of the rod by a nail. The propeller is rotated by rubbing the rod with another bar. A player can control the revolution direction of the propeller in two ways, by changing the gripping position or condition of the rod. This paper presents an experimental study on the mechanism of this toy. Main results of this study are that the revolution of the propeller is caused by the elliptical motion excited at the end of the rod, and that the vibration system can be represented by a lumped-constants model. Then, we reveal the mechanism of how the elliptical motion is generated by the player's operations.

Physics of the mechanical toy Gee-Haw Whammy Diddle

“…Within this paper, we have performed an extensive research of the device, aiming to pinpoint the essential phenomenon that causes the propeller to rotate. Contrary to the hypotheses presented in the previous works on this topic, in particular, works by Wilson 4 and Satonobu 3 , we have shown that an elliptical movement of the stick is not necessary to induce a rotational movement of the propeller – on the contrary, a purely linear motion of the stick induces the highest speeds of the propeller. We have also shown that contrary to ideas presented so far 4 , 5 , there is no synchronization effect between the motion of the stick and the propeller – by purely harmonic motion of the stick, the propeller was able to accelerate from rest to high frequencies (however not reaching the driving frequency), and the stabilized speed of the propeller was strongly dependent on the amplitude of the oscillations.…”

“…( 2) , the readings of the position of the nail are presented for two cases – one is elliptical, resulting from positioning the stick on the side of the subwoofer, and one straight and nearly vertical, when the stick is placed in the center. This shows that with our experimental device, we were able to mimic the outcomes produced in the close-to-original gee-haw whammy diddle in refs 3 , 4 . For elliptical movement, we confirmed the results obtained so far – the direction of the rotation of the propeller was predefined by the direction of the elliptical movement (areal velocity).…”

“…The fact that it is held in one hand and rubbed by the other does not allow any reasonable control over the excitation parameters – neither the exact position of the stick nor its movement. In previous works 3 , 4 , different mechanical devices were suggested that partially fixed the issue of holding the stick by hand, but kept the rather complicated way of stick excitation by rubbing. Although this does mimic the original idea of the device, it is connected to many complications.…”

“…Jun Satonobu et al . 3 provided presumably the most complex analysis of the problem so far, from both a theoretical and an experimental point of view. They confirmed the validity of the original hypothesis – that the rotation direction is determined by the elliptical movement of the end of the stick and the speed of the propeller by the magnitude of the areal velocity of the end of the stick.…”

Exhibition at `Summer-Holiday Science Square' hosted by the National Museum of Nature and Science

“…Girigiri-Garigari is a toy with a propeller that rotates through vibration [5]. It grew in popularity at the Acoustical Society of Japan's events, and it remains one of the most popular exhibits because participants can take the toy home after they make it (Fig.…”