Thevertical beam is 15.0 kg and 1.00 m long and thehorizontal beam

is 25.0 kg and 2.00 m long.

joinedbeams. Express your answer in the form

*x,y*, taking

theorigin at the corner where the beams join.

thejoined beams about an axis through the corner.

## Answer

mass of horizontal beam , M1 = 25 kg

mass of vertical beam, M2 = 15 kg

length of horizontal beam, L = 2m

height of vertical beam, H = 1m

center of gravity of horizontal beam, ( X1, Y1

)= ( L/2 , 0 ) = ( 1 m , 0 )

center of gravity of vertical beam , (X2, Y2 )

=( 0 , H/2) = ( 0, 0.5 m )

center of gravity of the combination,

(

Xcm , Y cm ) = [ ( M1 X1 + M2 X2 ) / ( M1 + M2 ) , ( M1 Y1+ M2 Y2 )

/ ( M1 + M2 ) ]

=

[ ( 25 / 40 ) , ( 7.5 / 40 ) ]

=

( 0.625 m , 0.1875 m )

Gravitational torque, τ = Force *perpendicular
distance from axis of rotation
=
( M1 g ) ( L/2 ) + ( M2 g ) ( 0 ) = 25 * 9.8 * 1 = 245 Nm