Rotational Motion and Law of Gravity

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Homework Help Overview

The discussion revolves around gravitational forces and torque in the context of rotational motion. The original poster presents two problems: one involving the calculation of two masses based on their gravitational attraction and total mass, and another concerning the torque exerted on a tooth by a dental bracket.

Discussion Character

  • Mixed

Approaches and Questions Raised

  • The original poster attempts to apply Newton's law of gravitation to find the individual masses from the total mass and gravitational force. They express confusion about isolating the masses. Another participant confirms the total mass relationship and suggests substituting one mass in terms of the other.
  • Participants question the correctness of their calculations and seek verification of their formula. There is an acknowledgment of a previous error in calculations, leading to a resolution for part a, while part b remains unresolved.

Discussion Status

Some participants have provided guidance on the gravitational problem, and one has successfully resolved it after identifying a calculation error. However, the torque problem remains open for discussion, with participants seeking further insights on how to approach it.

Contextual Notes

Participants are working within the constraints of homework assignments, which may limit the information they can share or the methods they can use. There is an emphasis on understanding the underlying principles rather than simply obtaining answers.

madeeeeee
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a) Two objects attract each other with a gravitational force of magnitude 9.30 x10-9 N when separated by 19.4 cm. If the total mass of the objects is 5.06 kg, what is the mass of each?

Heavier mass_______kg
Lighter mass______ kg

my attempt:
F=Gm1m2/r^2
so I rearranged to get m1 and m2 by itself and got (r^2)(F)/G=m1m2
5.247598=m1m2
but how do I get the mass for m1 and m2 separately is m1 + m2 = 5.06 kg?


b) A dental bracket exerts a horizontal force of 86.2 N on a tooth at point B in the figure. What is the torque on the root of the tooth about point A? (PLEASE SEE THE ATTACHMENT FOR THE PICTURE)

I know I need to break the forces up into components but I am lost on this question. Please help me! Thank you
 

Attachments

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madeeeeee said:
a) Two objects attract each other with a gravitational force of magnitude 9.30 x10-9 N when separated by 19.4 cm. If the total mass of the objects is 5.06 kg, what is the mass of each?

Heavier mass_______kg
Lighter mass______ kg

my attempt:
F=Gm1m2/r^2
so I rearranged to get m1 and m2 by itself and got (r^2)(F)/G=m1m2
5.247598=m1m2
but how do I get the mass for m1 and m2 separately is m1 + m2 = 5.06 kg?

Yes, the total mass is given as 5.06 kg, so m1 + m2 = 5.06 kg. Replace one of the masses, say m2, with m2 = (5.06 kg - m1).
 
I used this and found my answer to be .433 and 4.627 but its wrong. Do i have my formula correct?
 
madeeeeee said:
I used this and found my answer to be .433 and 4.627 but its wrong. Do i have my formula correct?

Your formula (Newton's law of gravitation) looks okay. Perhaps something went wrong in your math manipulations. If you post your calculations they can be checked.
 
actually I just solved it! It was just a silly error! But thank you for your help

Do you have nay idea how to do part b ?
 
madeeeeee said:
actually I just solved it! It was just a silly error! But thank you for your help

Do you have nay idea how to do part b ?

What are your thoughts? What do you think you need to know in order to proceed?
 

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