# How does inertia cause the water to stay in the bucket

• candypie90
In summary, inertia causes the water to stay in the bucket while spinning it vertically because of the tendency of objects to remain at rest or in a state of uniform motion. In circular motion, centripetal and centrifugal forces are involved, and if these forces are no longer applied, the bucket will fly off and the water will react due to inertia. The water will fall out of the bucket in the tangential direction that the bucket was moving, as inertia wants the water to continue moving in a straight line.
candypie90
Homework Statement: How or why does inertia cause the water to stay in the bucket while spinning it vertically?

I know inertia is the tendency of an object to remain at rest or in a state of uniform motion, but I am not exactly sure how it causes the water to stay in the bucket while it is spinning in a vertical circle.
Homework Equations: -

[Moderator's note: Moved from a homework forum as it is about the basic principle.]

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What do you know about circular motions? Are they uniform? Which forces are involved?

vanhees71
candypie90 said:
How or why does inertia cause the water to stay in the bucket while spinning it vertically?
You can look at it differently. It is not so much that the water stays in the bucket. It is that the bucket stays around the water. If any little bit happens to fly free, the bucket accelerates the rest of the water to catch up.

Heikki Tuuri
fresh_42 said:
What do you know about circular motions? Are they uniform? Which forces are involved?
I know that centripetal and centrifugal forces are involved

candypie90 said:
I know that centripetal and centrifugal forces are involved
So if forces are involved, where do you get your uniform motion from? Something has to literally force the bucket on its circle. If this force no longer applies, the bucket will fly off and the water will react due to inertia. Cp. post #3.

The bucket has a tangential velocity so if i cut the rope attached to the bucket (this is the radius) it would fly off in what ever the tangential direction was. I am confused? So the water is moving with the bucket in a uniform circular motion but when the rope is cut the water will fall out in what ever the tangential direction was of the bucket?

candypie90 said:
I am confused?
How would the water have to move to fall out of bucket? How does inertia want the water to move?

## 1. What is inertia?

Inertia is the tendency of an object to resist changes in its state of motion. This means that an object at rest will stay at rest and an object in motion will continue to move at a constant speed and direction, unless acted upon by an external force.

## 2. How does inertia cause the water to stay in the bucket?

The water in the bucket has inertia just like any other object. When the bucket is swung in a circular motion, the water also wants to continue moving in a straight line due to its inertia. However, the bucket prevents the water from doing so, causing it to "stick" to the bottom of the bucket and not spill out.

## 3. Does the amount of water in the bucket affect its inertia?

Yes, the amount of water in the bucket does affect its inertia. The more water there is, the more mass the bucket has to overcome in order to change its state of motion. This means that a bucket with more water will require more force to swing it in a circular motion and keep the water from spilling out.

## 4. Can the shape of the bucket affect how the water stays in?

Yes, the shape of the bucket can affect how the water stays in. A bucket with a wider base and a narrower top will have a lower center of mass, making it easier to swing without spilling the water. Additionally, a bucket with a smooth, curved bottom will create less turbulence and help the water stay in place.

## 5. Why does the water not spill out when the bucket is swung upside down?

When the bucket is swung upside down, the water is still subject to the same laws of inertia. The water wants to continue moving in a straight line, but the bucket prevents it from doing so. Additionally, the force of gravity is acting on the water, keeping it in place despite the upside down position of the bucket.

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