How much force does a ballerina apply to the floor when doing a turn??

Question:science fair :]

Best Answer - Chosen by Asker: science fair :]

You didn't say what grade are you in, so I don't know much detail should I go in.

First of all, let's be clear on terminology. In science, we can't use "force" and "power" interchangeably, as well as "mass" and "weight". "Force" is not to be confused with "pressure", too.Also be careful with "momentum" and "energy". Since it's science fair you will have to sound like a scientist and speak the same language with your science teacher. Rather than showing how much ballet technique you know, you will need to show how much science you understand. All other answers are fantastic, but as a science teacher I don't quite like what I see. People say what they feel or are aiming to feel rather than what actually happens to the floor in reality. Dance teacher tells you what you supposed to do in order to dance rather than what it scientifically is. Otherwise everyone would be able to learn to dance from reading a science book.

The useful rephrasing of your question is "What would the bathroom scale read if ballerina were dancing on it?" OK, don't attempt dancing on the scale or you will ruin it. Just imagine it. You can try standing on it and pulling up - you will see that the reading doesn't change. Pulling up is your feeling.

Now let's think what kind of forces she CAN apply. Obviously, one is the downward force prependicular to the floor and another one is the force of friction that's hard to say which direction it is, but definitely parallel to the floor.

There is a force perpendicular to the floor which has two components. One - she always exerts the force due to gravity. This force is calculated by mutliplying her mass by the acceleration due to gravity. F = mg. This part is trivial, but you should show that you know about it. There are no other component to a perpendicular force if she is not accelerating up or down. When she is initiating a turn then she is accelerating, and there is an extra component to this perpendicular force.

It will be difficult to calculate but possible to estimate. I don't know what grade are you in. You can estimate it by using the concept of impulse if you know what it is. If no - don't worry about this part. Just mention that there is extra force due to pushing off.
You can estimate the friction force from measuring her angular velocity at the start of the spin when she's done generating the angular momentum (not an easy task!) and measuring how many turns degrees can she turn until she stops.

Downward force has nothing to do with her angular velocity i.e. how fast she turns. But since ballet turns are not like spinning a top or a wheel, and she's actually using the floor to generate her own momentum at different instances in time, it becomes rather complicated question.
This question could get more meaningful answers in physics section. E-mail me if you need help.

not too much, since ballerinas eat very little.

That depends on her weight and how fast she turns.

one her toes or just her foot on her toe she would be better off to put more force than on flat foot on flatt foot she needs more speed than anything hope it helps
shorty

That depends on the dancer and how much she weighs as well as what type of turn she is performing.
A lot of it has to do with the momentum required. But dancers are taught to "think up". Most of the momentum is carried out through the legs and arms, not the feet. But before the turn, like the preparing plie or the jump, requires a lot of force.

not much because if you force the ground you'll fall, and you just think straight up.

Not that much, too much and it will whip you around and you'll lose your balance. (I used to put way to much pressure on the floor) Minimal pressure.

There are a lot of turns of ballet so I cannot cover all of them. But I can tell you basically what forces are applied by the ballerina's body to the floor in several of the common ballet turns.....

1. pirouette in passe position
[A "passe" is when the ballet dancer raises her lead
foot so that the lead foot's toe touches the knee.]
Especially when the ballerina turns, force is delivered to
twice the size especially when she is in releve when
turning in passe position.

2. fouette (or "whipped" turn)
On the stops in the continous turns, force is applied to the
area of the knee and to the ball of the foot as it lands only
about 1/4 second before the next fouette turn. Because
of the constant changes in turns in the fouettes, on the
"landings", the forces are 2X stronger to the floor, and on
the actual turn, only about 1X stronger.

3. pirouette continue ("continous pirouette")
This occurs especially in the "pas de deux", when the
pirourette is assisted by her dance partner. Force is
applied to the floor at twice the force since the pirouette
brings the dancer in "releve" position throughout the turn.

Enough force to keep her/him up but not too much if it causes the knee to lock otherwise, you can easliy lose balance. Also, it's better to flex the cheek of the standing leg and relax the muscle of the leg in passe.

not to much if a double sints it is not that many single will be very little

its not so much force, its getting enough momentum to turn and keep the momentum going with spotting and fouettes as well demonstrate this. if we push to hard we move our center and loose our balance forcing us out of the turn. so when we prep, we just find our center and keep it there, pushing off with a force we've found works best for us and lifting up sort of as well.

for leaps its a different story. we use a lot of power to get up off the ground high enough to straighten our legs or to switch legs or to jump "to" a male partner. but turns not to much. hope this helps!

Nobody seems to get the question. You're not asking about rotation...
Remembering that all actions motivate from the center - the harder you press your pointe shoe/foot into the floor the faster you turn. The answer is a complete and full stretch/extension into the floor. As hard as you can while you turn. From the center up, you lift up.
According to physics, all upward movements motivate from a downward force. And I quote..."Every action has an equal and opposite reaction.." When we watch dance we see the "reaction." For the dancer be fully up on pointe, they must press the pointe fully down into the floor.
You cannot avoid weight on your toes. Anyway, if the shoe fits right, the harder you press, the less it hurts. And then there's toe shoe heaven, when nothing hurts!

depending if the dancer is doing a single pirouette (turn) or double or triple.

Single: Not much force AT ALL

Double: Small force,but not to much

Triple or Higher: You need force to get your body to do three or more turns. But keeping your arms still and tight in a position.

You use alot of force especially when you turn and it depends on the number of turns and the kind of turn your doing.

Good luck