Impact force on a falling object that spreads

In summary, the conversation discusses the phenomenon of hydraulic jump and its relation to the impact force. The equation F = mgh/s is suggested for calculation, but there is uncertainty about what should be used as the "slow down distance" and how to demonstrate it on a graph. The idea that the jump occurs when the water has slowed down enough is mentioned, and there is a suggestion to use the radius as the slow down distance. There is also a discussion about comparing the height and density of water to see which affects the radius more, and the idea of using the gradient of F as a comparison point on a graph is proposed. Additionally, there is a discussion about the difficulty of determining the exact point where the fast water has slowed enough to
  • #1
MelanieBrett
7
0
Hi,

Homework Statement


I'm doing some research into the hydraulic jump and was wanting some help in calculating the impact force.
Hydraulic jump is a phenomenon to do with the turbulence of the water - it is the 'ring' around the stream of water when a tap is turned on

Homework Equations


The equation I have found to use is:
F = m g h / s

3. The Attempt at a Solution

I have the mgh, and was wondering what to use as the slow down distance.
I have been saying in my essay that the jump occurs when the water has slowed down enough. If that is my argument, then should I be using my values of the radius as the slow down distance?
Also, how should I be demonstrating it on a graph? Two of my experiments I wanted to compare were the height above the surface (h) and the density of water I was using (m) to see which affected the radius more. g is really the only constant, and there is no set variable (because I'm comparing two of them to see which affects the radius the most) - so what advice would you have?
Many many thanks, and I do apologise if this is a little incoherent; I'm quite tired and need to get this done soon :)
Update: Maybe if F were the gradient, then that would be easily comparable, so mgh on x-axis, and s on the y??
 
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  • #2
Yes, I believe the radius is the point where the fast water has slowed to a critical value, where it matches the speed the wavefront would have on still water. (But since that speed would depend on the height of the jump, I'm not sure how one figures out exactly where that will be.)
In a channel it would be more straightforward, but in a ring the fast water is thinned as it spreads from the source. I suspect that means the water speed drops faster as it moves out, there being less thickness of water to maintain momentum against the constant drag. I.e., in regards to the equation you quote, F might increase with radius. (I'm thinking that your F is really a force per unit width of flow.) That would mean you need to integrate over the radius.
 

FAQ: Impact force on a falling object that spreads

What is impact force?

Impact force is the amount of force exerted on an object when it collides with another object or surface. It is measured in Newtons (N).

How is impact force calculated?

Impact force can be calculated by multiplying the mass of the falling object by its acceleration due to gravity (9.8 m/s²) and its velocity at impact. The formula is F = m * a * v.

How does the spread of a falling object affect impact force?

The spread of a falling object, also known as its surface area, can greatly affect the impact force. A larger surface area means the force is distributed over a larger area, resulting in a lower impact force. Conversely, a smaller surface area leads to a higher impact force.

Can impact force be reduced?

Yes, there are several ways to reduce impact force on a falling object. These include increasing the surface area of the object, decreasing its mass, or adding cushioning materials to absorb the force.

What are the real-life applications of studying impact force?

Understanding impact force is important in a variety of fields, including engineering, sports, and safety. It can help engineers design safer structures and equipment, coaches train athletes to prevent injuries, and researchers develop better safety measures for various activities.

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