# Why does a spinning ice skater’s angular velocity increases as she brings her arms in toward her body?

## Why does a spinning ice skater’s angular velocity increases as she brings her arms in toward her body?

When she moves her arms close to her body, she spins faster. Her moment of inertia decreases, so her angular velocity must increase to keep the angular momentum constant.

## Why is it harder for an ice skater to spin with his arms stuck out as opposed to tucked in?

Moment of inertia depends on both the mass of an object and on how that mass is distributed. The farther from the axis of rotation the mass is located, the larger the moment of inertia. So your moment of inertia is smaller when your arms are held at your sides and larger when your arms are extended straight out.

## What happens when a skater throws her arms outward?

For example, when the skater extends her arms outwards, increasing twofold the moment of inertia, the velocity of her spin also decreases twofold. While tucking her arms in, she decreases the moment of inertia significantly and thus gains high rotational velocity.

## What happens when a spinning ice skater draws?

The “scratch spin” is a classic figure skating maneuver in which the skater draws her arms and leg in, which causes her angular speed to increase. This is the result of conservation of angular momentum.

## When an ice skater spins and increases her rotation rate by pulling her arms and leg in what happens to her rotational kinetic energy?

Her angular momentum is conserved because the net torque on her is negligibly small. In the next image, her rate of spin increases greatly when she pulls in her arms, decreasing her moment of inertia. The work she does to pull in her arms results in an increase in rotational kinetic energy.

## Why does the ice skater twirls faster and faster as she retracts her arms closer to her body?

When the hands and legs are brought close to the rotational axis, the rotational inertia decreases thereby increasing the skaters angular velocity as per the conservation of angular momentum. Increase in angular velocity implies increase in the kinetic energy.

## Why does a spinning ice skater spin faster when he pulls his arms in?

The principle of the conservation of angular momentum holds that an object’s angular momentum will stay the same unless acted upon by an outside force. This explains why a figure skater spins faster when she tucks her arms in close to her body.

## Why does a figure skater spin faster when she has her arms closer to her chest and spin slower when she has her arms stretched outwards?

The principle of the conservation of angular momentum holds that an object’s angular momentum will stay the same unless acted upon by an outside force. This explains why a figure skater spins faster when she tucks her arms in close to her body.

## When a spinning figure skater pulls his arms in close to his body what happens to his moment of inertia?

There is a classic example that a spinning skater pulls his arms back. The angular momentum is conserved, the moment of inertia decreases. And therefore, it’s angular velocity increases, so the rotational kinetic energy will increase.

## When a skater pulls her arms inward?

The source of this additional rotational kinetic energy is the work required to pull her arms inward. Note that the skater’s arms do not move in a perfect circle—they spiral inward. This work causes an increase in the rotational kinetic energy, while her angular momentum remains constant.

## Why do skaters put their hands above their head?

One of the benefits of jumping with the arms up is to learn better take-off movements, particularly with the arms. Jumping with one or both arms over head helps because the skater is often more likely to pivot all the way through to forward on the jump take-off with a better body line.

## What causes an increase in angular velocity during a spin?

The angular velocity increases because the moment of inertia is decreasing.

## What happens to her angular speed when she pulls her arms in?

When she pulls her arms in, her rotational inertia is reduced. Since there is no external net torque on the ice skater, her angular momentum remains constant because her angular velocity magnitude increases.

## What happens a spinning ice skater draws in her outstretched arm?

As the ice skater draws her arms in, the moment of inertia with respect to the axis decreases. Therefore in order to conserve the angular momentum the angular velocity has to increase.

## Why an ice skater stretches out arms and legs during performance?

During the course of their performance, an ice skater, a ballet dance or an acrobat take angular of the principle of conservation of angular momentum (i.e Iω= constant), by stretching out arms and legs or vice-versa. On doing so, their moment of inertia increases/decreases.