Circular motion of bucket of water

In summary: Do you know how to do this?In summary, the moon orbits the Earth at a distance of 3.85 X 10^8m. The Earth's mass is 5.98 X 10^24kg and the formula to find the period of a motion is T=2 Pi (r^3/2) / square root of GMe. The moon's period is about 30,000 days.
  • #1
alchemist
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0
when a bucket is filled with some water, you take it up and swing it around, if you swing it hard enough, the water in it would not spill out, why is this so?is it because the reaction force from the centre of rotation is acting on the water?
 
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  • #2
In order to move the bucket out of a straight line, you have to apply force to it (this is the "centripetal" force). If you swing it fast enough, the force you are applying to the bucket (and so the 'reaction force' as you put) will be greater than the force of gravity.
 
  • #3
To calculate this force you might need this:

F = m*v^2/r

F = the centripetal force (i don't know if this is a correct word )

m = mass

v = velocity

r = distance
 
  • #4
Originally posted by HallsofIvy
In order to move the bucket out of a straight line, you have to apply force to it (this is the "centripetal" force). If you swing it fast enough, the force you are applying to the bucket (and so the 'reaction force' as you put) will be greater than the force of gravity.

If that didn't quite clarify it enough:

When you swing the bucket in a circle, there is a force pulling toward the center of rotation, which would probably be at your shoulder. When the bucket is above your head, that force is pulling downward. If you are swinging fastly enough, the force generates acceleration that is greater thant the acceleration due to gravity. So the water cannot escape from the bucket due to gravity, because the bucket is accelerating downward faster than gravity is causing the water to. It's like trying to run away from an olypmic runner. Basically, as long as the water and bucket are putting a substantial amount of pressure on each other, the water won't fall out of the bucket.
 
  • #5
Another way to explain it: When the bucket is at the top of the rotation facing downward, the water is accelerating down out of the bucket. But your force exherted on the string is accelerating the bucket down FASTER than the water can accelerate out of the bucket. So the water stays in the bucket.
 
  • #6
I just wonder...

In the bucket you are swinging around you put a piece of wood,
if the bucket is above your head, will the wood be at the same level
in the water as it was in rest ?

this question was asked during a science quiz here in Holland.
Really nobody knew the answer, nor had any idea, maybe one of you?
Ton
 
  • #7
I would think the block would stay at the same level. The change in acceleration would be analogous to changing the acceleration due to gravity.
 
  • #8
The reason why the water does not leave the bucket is because the water is wanting to travel in a straight line but is being forced to turn with the bucket because it has no where else to go. Just like when you are on a rollercoaster and doing a loop. Say you are traveling, with a ball in your hand, in a straight line going pretty fast and were about to do a loop and just before you went up to start the loop you let go of the ball. The ball would keep going in a straight line as you were turning up and it would seem as if the ball fell to your feet. This is why...
 
  • #9
The water doesn't fall because of the same reason that the moon doesn't fall to the earth. Even though it is being pulled by it.

Due to the velocity that it has, at every point in its motion, it deviates from the path of falling, and due to the force of gravity, from following a tangential path.

And what keeps the bucket from flying off is your hold on it.


spacetime
www.geocities.com/physics_all/index.html
 
  • #10
The definitive accommodation of your question can be answered in a recording by Dr. F. Zappa where he not only describes centripetal motion and it's local effects , but also is the first noted mention of string theory, The essay is entitled ," Moving to Montana soon".

The man died rather young after contracting probate cancer by exposure to Tipper Gore,
 
  • #11
Hi..my question is on finding the period for the moon's motion around the earth. I need to express my answer in days and compare it to the length of a month. The moon orbits the Earth at a distance of 3.85 X 10^8m. The mass of the Earth is
5.98 X 10^24 kg. I know that I am supposed to use the formula T=2 Pi (r^3/2) / square root of GMe, and then when I get my answer for that I divide by 86400 to express my answer in days. I think my answer should be somewhere around 27.153 days, but I am not getting anything close to that. I have worked and worked the problem out and I just cannot solve it. I think I may be using my calculator incorrectly. I am coming up with an answer of 2.68^11 and then when I divide that by 86400 I get 3101851.852, which is very wrong. Please help!
 

1. What is circular motion of a bucket of water?

Circular motion of a bucket of water refers to the movement of a bucket filled with water in a circular path. This type of motion is caused by the combination of two forces: gravity, which pulls the bucket downwards, and centripetal force, which pulls the bucket towards the center of the circular path.

2. What causes the water in the bucket to stay in the bucket while it is in circular motion?

The centripetal force, provided by the bucket's circular motion, acts as a "centripetal barrier" that prevents the water from spilling out of the bucket. This force is strong enough to counteract the centrifugal force, which would push the water outwards due to the bucket's circular motion.

3. Can the speed of the bucket affect the water inside?

Yes, the speed of the bucket can affect the water inside. As the speed of the bucket increases, the centripetal force also increases, which makes it easier for the water to stay in the bucket. However, if the speed is too high, the centrifugal force may become stronger than the centripetal force, causing the water to spill out of the bucket.

4. How does the shape of the bucket affect the circular motion of the water?

The shape of the bucket can affect the circular motion of the water in two ways. Firstly, the shape of the bucket can determine the direction of the centripetal force, which is essential for keeping the water in the bucket. Secondly, the shape of the bucket can also determine the distribution of the centrifugal force, which can influence the stability of the water in the bucket.

5. What are some real-life applications of circular motion of a bucket of water?

Circular motion of a bucket of water has various real-life applications, such as in amusement park rides, where people sit in a spinning bucket while the centrifugal force keeps them from falling out. It is also used in washing machines, where the spinning motion helps to remove dirt and stains from clothes. Additionally, circular motion of water is also used in centrifuges to separate substances based on their density.

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