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## Homework Statement

Attached is the picture of a dumbbell. I do not understand how the coordinate of M

_{1}is

M

_{2}R/ (M

_{1}+ M

_{2})

It is not an assignment question but an example from a book.

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- Thread starter rsaad
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- #1

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Attached is the picture of a dumbbell. I do not understand how the coordinate of M

M

It is not an assignment question but an example from a book.

- #2

ehild

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ehild

- #3

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because CM=0, I get M

which further gives me

R

=|

- #4

ehild

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_{1}m_{1}+R_{2}M_{2})/M_{1}+M_{2}

because CM=0, I get M_{1}R_{1}= -R_{2}M_{2}

which further gives me

R_{1}= RM_{2}/ (M_{2}-M_{1})

=|

What do you mean on R

How are R1 and R2 related to the distance R between the spheres?

ehild

- #5

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R= R_1 + R_2

where R_i is the distance to M_i from CM.

where R_i is the distance to M_i from CM.

- #6

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In the book R_1 = R M2/ (M1 + M2) but mine is R1= R M2 / (M2-M1)

- #7

ehild

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If x1, x2 are coordinates of m1, m2, respectively, the x coordinate of the CM is (x1m1+

x2m2)/(m1+m2).

If they are distances from the CM, the coordinate of m2 is negative: m1R1-M2R2=0

ehild

x2m2)/(m1+m2).

If they are distances from the CM, the coordinate of m2 is negative: m1R1-M2R2=0

ehild

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