Calculate the mass when not hanging it in dynamometer

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To calculate the mass of an object without hanging it on a dynamometer, static friction (µs) can be utilized. The user can drag the object using the dynamometer to measure the force in Newtons. By knowing the coefficient of static friction and the force measured, the mass can be calculated using the relationship between frictional force and weight. Clarification on the term "dynamometer" was provided, emphasizing its use in measuring force rather than mass directly. This method allows for the determination of mass without suspending the object.
Elzz
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Homework Statement


Hello! I have a physics problem that I can't solve. I'm supposed to describe how I can calculate the mass when knowing the µv (I don't know the english term but I'm guessing friction...something (friction when the object is not moving)). You are allowed to use a dynamometer but you are not allowed to hang the object (that I want to know the mass of) in it. I have nooo idea how to solve it haha.

Homework Equations


..

The Attempt at a Solution


I thought that maybe i could drag the object with the dynamometer and then know the N, but i dunno? haha please help.
 
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Welcome to the PF. :smile:
Elzz said:
µv (I don't know the english term but I'm guessing friction...something (friction when the object is not moving)).
The term is probably "static friction" or µs. That is used when two surfaces are moving together and not sliding past each other.

Elzz said:
You are allowed to use a dynamometer but you are not allowed to hang the object (that I want to know the mass of)
Can you post a picture or diagram of what you call a "dynamometer"? I'm familiar with the term, but only in the context of measuring motor power and torque, not in the context of measuring the coefficient of friction or a mass. Thank you.

EDIT/ADD -- You can attach a PDF or JPEG file to your reply by using the "Upload" button in the lower right corner of the Reply/Edit window. :smile:
 
berkeman said:
Welcome to the PF. :smile:

The term is probably "static friction" or µs. That is used when two surfaces are moving together and not sliding past each other.Can you post a picture or diagram of what you call a "dynamometer"? I'm familiar with the term, but only in the context of measuring motor power and torque, not in the context of measuring the coefficient of friction or a mass. Thank you.

EDIT/ADD -- You can attach a PDF or JPEG file to your reply by using the "Upload" button in the lower right corner of the Reply/Edit window. :smile:
Thank you for responding!

https://www.google.se/search?q=dyna...B&biw=360&bih=512#imgrc=d3cklw9wGJhFCM:&isa=y

This is a dynamometer. If you hang an object in the hook of it you can measure the force (in Newton) and then calculate the mass.
 
Elzz said:

The Attempt at a Solution


I thought that maybe i could drag the object with the dynamometer and then know the N, but i dunno? haha please help.

That sounds correct to me. You just need to describe the method in more detail.
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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