# Physics- center of mass problem ?

J.live

## Homework Statement

The coordinates of the center of mass for the extended object shown in the figure are (L/4, −L/5). What are the coordinates of m1? (Assume m1 = 4 kg, m2 = 2 kg, and m3 = 3 kg. Use any variable or symbol stated above as necessary.)

Here is the diagram : http://tinypic.com/view.php?pic=33da26e&s=7[

Can someone check my work?

4(x,y) + 3(-L/4,-3L/10) + 2(-3L/4,-L/4) = 0

-( 4x,4y) +(-3L/4,9L/10) + (-3L/2,-L/2) = 0

-4x - 3L/4 - 3L/2 = 0

-4y + 9L/10 - L/2 = 0

-4x = 9L/4

-4y = 4L/10

x = -9L/16

y = -L/10

P.S. please let me know what errors I made, if any.

Thanks.

## Answers and Replies

J.live
Help :/?

Science Advisor
Homework Helper
Gold Member
What axis have you chosen for calculating the moments of the masses? For the c.m. about the x axis, it's m1y1 + m2y2 + m3y3 = (m1 + m2 +m3) Y_c.m. , where the y1, y2, anmd y3 terms are the respective distances from the x axis, and Y_c.m. is given as -L/5.

seansharpzy
two forces whose resultants is 100N perpendicular to each other,if one of them makes an angle of 60 degrees with the resultants,calculate its magnitude?

Science Advisor
Homework Helper
Gold Member
two forces whose resultants is 100N perpendicular to each other,if one of them makes an angle of 60 degrees with the resultants,calculate its magnitude?
Sean, please post this as a new topic and show an attempt at a solution. Thanks.