Question

doing webwork when i came across this question. sure i had it right but apparently im not.

The weightless horizontal bar in the figure below is in equilibrium. Scale B reads 4.20 kg (N.B. as you know, the scale should read N, but no one told the manufacturer). The distances in the figure (which is not to scale) are: D1 = 8.5 cm, D2 = 9.0 cm, and D3 = 5.0 cm. The mass of block X is 0.91 kg and the mass of block Y is 1.97 kg. Determine the reading on scale A. and mass of block Z.

(look up "massless beam torque and 2 scale" and itll be the fourth pic on google)

I made the spot where z and scale b is, the center of rotation therefore.

Net torque= -Ta + Tx + Ty = 0
-(0.09+0.085+0.05)Ta = -(0.05+0.09)(0.91*9.8)+(0.05)(1.97*9.8)

(excluded sin(angle) because all angles are 90 degrees)

-0.14Ta =_ (1.24852+0.9653)
Ta = 9.8392 N or in this case; 9.8392 kg.

I cant solve for the second question until i get the first answer.

Answer 1

nevermind. figured out that the "mass" of the blocks are actually the weight so i unnecessarily multiplied them by 9.8