Determining the 'Instantaneous Force' during impact

In summary, the conversation discusses calculations on the impact force of a falling object and how it relates to the use of heavy weights on belt conveyors. The concept of average force and its relation to kinetic energy and distance is also explored, with the question of graphing the force during deceleration and finding the instantaneous force being raised. The conversation also touches on friction and the need for an average force in calculations, with further research and information being sought on the force curve and its uniformity.
  • #1
structengine
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I have been doing some calculations on a falling object and its impact force. We use heavy weights on our belt conveyors to maintain tension on the belts. One of our calculations relates to the amount of force placed on the structure that one of these weights lands on. I have the calculations and the answers, but as a matter of curiosity, I started looking at the formulas a little closer. The force of impact is Favg. Since this force is the change in Kinetic energy divided by the distance after impact, it seems to me that this is the average force over that distance. Is there a way to graph this force during deceleration? How can the instantaneous force (for lack of a better term) be found? Is there a formula that I am overlooking? Not having to work very often with the dynamics of the structures I engineer, my physics in this area is very rusty, and being a pretty new engineer, I like to dig a little deeper into the things I am doing. Can anybody help? Thanks
 
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  • #2
Your logic is correct since work done = gain in KE = Force x distance
When a weight lands on the conveyor belt there is slipping between the weight and the belt.
This friction force is what acts on the weight and speeds it up to the speed of the conveyor belt. When the weight is up to speed there is no resultant force on the weight. So the foirce on the weight starts at some 'high' value and decreases to zero.
You must use the average force to calculate the gain in energy.
If the force decreases uniformely then the maximum force will be 2 x the average force.
If there was no friction (ice covered conveyor !) I think you could say that the weight would not be accelerated up to the speed of the conveyor belt.
This is not a particularly rigorous analysis but I hope it goes some way to explain why an average force is needed in any calculation.
 
  • #3
That makes sense for using the average force. Since the force does change between the initial energy and the final energy with respect to the distance traveled it would have to be the average over that distance. I don't know if the force changes uniformely over that distance though. I am using a crushable honeycomb product to 'catch' the takeup weight, and so I can probably find out from them what the force curve looks like. Thank you
 

1. What is meant by "instantaneous force" during impact?

"Instantaneous force" refers to the force that is exerted on an object at a specific moment during a collision or impact. It is the force that is applied to an object in a very short amount of time, usually at the point of contact.

2. How is instantaneous force determined during impact?

Instantaneous force can be determined by measuring the change in momentum of an object during impact. This can be done by calculating the difference in velocity of the object before and after the impact and using the formula F = mΔv/Δt, where F is the force, m is the mass of the object, Δv is the change in velocity, and Δt is the time interval.

3. What factors can affect the instantaneous force during impact?

The instantaneous force during impact can be affected by factors such as the mass and velocity of the objects involved, the angle and speed of the impact, and the elasticity of the materials involved. Other factors, such as air resistance and friction, can also influence the force.

4. Why is it important to determine the instantaneous force during impact?

Determining the instantaneous force during impact is important in understanding the dynamics of a collision or impact, and can help in predicting the outcome of such events. It is also crucial in designing safety measures and protective equipment to minimize the effects of impact forces on individuals and objects.

5. Are there any real-life applications of determining the instantaneous force during impact?

Yes, there are many real-life applications of determining the instantaneous force during impact. For example, in the field of sports, calculating the instantaneous force can help in improving techniques and preventing injuries. In engineering, it is used in designing structures and vehicles to withstand impact forces. It is also used in accident reconstruction and analyzing the effects of collisions in car safety testing.

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