Question

To determine the location of his center of mass, a physics student lies on a lightweight plank supported by two scales L - 2.55 m apart, as indicated in the figure below. Ir the left scale reads 284 N, and the right scale reads 115 N, calculate the student's mass Sumit Answer Tries 0/8 Calculate the distance from the student's head to his center of mass Sumt AnswerTries 0/8

Answer 1

F1 = 284 N , F2 = 115 N , L = 2.55 m

Here the two forces F1 and F2 are acting upwards and his weight acting downwards.

Then ΣFy = F1 + F2 - W = 0

W = F1 + F2

mg = F1 + F2

m = ( F1 + F2 ) / g

m = (284 + 115) / 9.81

m = 40.67 kg

b)

principles of torque

Στ = LF2 - XW = 0 here X is the center of the mass.

LF2 = X(mg)

X = (L*F2 ) / (mg) = [ 2.55 *115 ] / [ 40.67*9.8]

X = 0.734 m