How to determine minimum required force in an applied context

[kbupshaw]

Hello,

I am a graduate student in psychology and I've encountered an issue in one of my studies that is outside of my expertise, but hopefully within one of yours.



Here's my predicament:

I recently conducted a study with infant participants that investigated infants' ability to solve a simple problem involving two blocks of differing mass (one 70 grams and the other 470 g.) and a piece of cloth. The problem that infants must solve is this: one block is placed on top of the cloth, such that the block itself is out of their reach, yet the cloth is within reach, so infants must pull the cloth in order to retrieve the supported block. To publish my findings, I am being asked to report:

1) for the 470 g block, what is the amount of force required to break static friction between the cloth and the table beneath it (which would cause the supported block to begin to move)?

2) for the 70 g block, what is the amount of force required to break static friction between the cloth and the block, such that the cloth would move separately, leaving the block behind?

In solving #1 and #2, all factors are identical (e.g., direction of force, acceleration, materials of the item, etc.) except for the mass of the block and the point of breaking static friction. I created a force diagram to better illustrate my problem---please overlook/forgive my lay explanation and terminology (i.e., I didn't include normal force or gravity in the diagram). Importantly, I am more concerned with the relative relation between the force required in these two situations, rather than the absolute value.

What I'm wondering is, what is the best way to answer this problem? Is it possible to solve the problem in the abstract, that is, filling in approximationis for the relevant variables? Any suggestions you have are appreciated. Thanks

 

[Achy47]

for your time!Dear graduate student in psychology,

Thank you for sharing your study with us. Your predicament is certainly an interesting one and I am happy to provide some guidance on how to approach it.

Firstly, it is important to note that the force required to break static friction is dependent on several factors including the mass of the blocks, the coefficient of static friction between the cloth and the table, and the force applied to the cloth. Therefore, in order to accurately determine the force required in each situation, it is necessary to conduct experiments with different variables and measure the force required in each case.

One approach you could take is to use a force sensor to measure the force required in each situation. For the 470 g block, you could place the block on the cloth and gradually increase the force applied to the cloth until the block starts to move. This would give you the force required to break static friction between the cloth and the table. Similarly, for the 70 g block, you could place the cloth on top of the block and gradually increase the force applied to the cloth until it starts to move separately from the block. This would give you the force required to break static friction between the cloth and the block.

Another approach could be to use mathematical equations to approximate the force required in each situation. However, this would require accurate measurements of the coefficient of static friction between the cloth and the table, as well as the cloth and the block. These values can vary depending on the materials used, so it may be more accurate to conduct experiments and measure the force directly.

In conclusion, the best way to answer your problem would be to conduct experiments and measure the force required in each situation. This would give you the most accurate results and allow you to report the data in your study. I hope this helps and best of luck with your research.