1.
Fart A stant If you ignore the weight of the bar itself, how far from the left end of the barbell is
the center of gravity? Express your answer to three significant figures and include the
appropriate units A 1.80-m-long barbell has a 20.0 kg weight on its left end and a 36.0 kg weight
on its right end You may want to review (Pages 204- 205) HA Submit Previous Answers
Request Answer X Incorrect; Try Again Part B Where is the center of gravity if the 7.00 kg mass
of the barbell itself is taken into account? Express your answer to three significant figures and
include the appropriate units HA dValue Units
Solution
Part A : If we ignore the weight of the bar itself, how far from the left end of a barbell is the
center of gravity?
we know that, x cg = (m 1 x 1 + m 2 x 2 ) / (m 1 + m 2 )
x cg = [(20 kg) (0 m) + (35 kg) (1.8 m)] / [(20 kg) + (35 kg)]
x cg = (63 kg.m) / (55 kg)
x cg = 1.14 m
Part B : Where is the center of gravity if the 7 kg mass of a barbell itself is taken into account?
we know that, x cg = (m 1 x 1 + m 2 x 2 + m 3 x 3 ) / (m 1 + m 2 + m 3 )
x cg = [(20 kg) (0 m) + (35 kg) (1.8 m) + (7 kg) (1.8 m / 2)] / [(20 kg) + (35 kg) + (7 kg)]
x cg = [(63 kg.m) + (6.3 kg.m)] / (62 kg)
x cg = [(69.3 kg.m) / (62 kg)]
x cg = 1.11 m