Action Ski DancerAntonius Krisna MuktiEver watch the performances of dancers ice skating? One of its attractions is the dancer spins like a top. Initially
slow, eventually spinning rapidly, accompanied by the dancers
outstretched hand, then folded into concurrently with increasing speed. at the end of the attractions, dancer stretching his arms back and turning the speed down. Monotone, huh? But the attraction is no scientific basis.Because
there is an element of rotation, then it's attractions including the
rotational motion so that the units are different from ordinary straight
motion. One
of them is the moment of inertia (l), which is defined as the product
of the mass of a particle (m) by the square of the distance from the
pivot point particle (r). So, l = m x r2. Unit rotational velocity of the angular velocity (w).In rotational motion is also a unit similar to the linear momentum (p = m x v), the angular momentum (L). Angular momentum is synonymous with linear momentum, equal to the product of the moment of inertia with angular velocity. The law of conservation of angular momentum reads, if there is no
resultant moment of external forces acting on the system, then the
system angular momentum is conserved.When the dancer stretching his arms or one leg, which he acquired angular velocity is low. With his arms folded or pressed his foot, the dancer zoomed moment of inertia of the shaft. Because r decreases (with folded hands), then l-shrunk, too. Furthermore, because of the constant angular momentum, angular velocity w enlarged. Thus, the penaripun spin faster.For clarity, let's see. For
example, a dancer has a moment of inertia of 4.0 kgm2 when arms
outstretched (l1) and 1.2 kgm2 when both hands fastened to the body
(l2). If
during outstretched arms angular velocity of 1.8 revolutions per-second
(w1), we can calculate the round when his hands move closer to the body
(w2). Because L is constant, then L1 = L2. By remembering L = l x w and enter the respective sizes obtained w2, ie 6 rounds per second.Well, look! angular velocity increased more than three times that number. So, it should be.Source: Intisari (January 2004)
0 Response to "Action Ski Dancer"
Post a Comment