What the heck is moment of inertia?
Simply put, moment of inertia[1], or rotational inertia, is how hard something is to turn. You may have heard of Newton’s second law, which is force equals mass times acceleration. This law describes things that are moving in a straight line. Whenever we start doing turns, however, we turn towards the rotational version of it, which is, torque equals moment of inertia times angular acceleration.
Read MoreHave you ever watched those wonderful videos of ballerinas holding very, very long balances, and wondered, how on earth do they do that? Then, if you’re like me, do you go immediately into asking, could I ever do something like that, because just letting go of the barre in class is a struggle?
Read MoreIf you have ever tried landing a jump with straight legs, you would immediately feel the impact rattling your ankles and knees and maybe even all the way up to your shoulders. But, when we land our jumps in a plié like our teachers told us, we feel less impact upon landing. But why does this happen? And what’s the physics behind it?
Read MoreWhen we do a plié, we bend our knees, and therefore, the length of our legs contract. When we go back up, our knees straighten up again, and the length of our legs returns to what it was. This is called an oscillatory motion, which is a motion that oscillates around an equilibrium in position [2]. For the case of pliés, this motion is the up and down motion between the very top of the plie (legs fully straight) and the very end of the plié (knees half bent or fully bent depending on if you are doing a demi-plié or a grand-plié). We can define the equilibrium as the position at the very top of the plié, with the legs fully straight.
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