Phys101
Term: 122
Online HW-Ch09-Lec01
Q1:
The two pieces of uniform sheets made of the same metal are placed in the x-y plane
as shown in the figure. The center of mass (x com , y com ) of this arrangement is located
at:
A.
B.
C.
D.
E.
First quadrant
Second quadrant
Third quadrant
Fourth quadrant
Origin
Ans:
B
Q2:
Four masses, m 1 = 1.0 kg, m 2 = 2.0 kg, m 3 = 3.0 kg and m 4 = 4.0 kg are placed at the
corners of a square of side a = 1.0 m, as shown in the figure. Find the magnitude of
the position vector (in m) of the center of mass. (Give your answer in three
significant figures form)
Ans:
xcom =
m1 x1 + m2 x2 + m3 x3 + m4 x4
M
=
=
ycom =
=
=
1×0+2×1+3×1+4×0
1+2+3+4
5
= 0.5 m
10
m1 y1 + m2 y2 + m3 y3 + m4 xy4
M
1×0+2×0+3×1+4×1
1+2+3+4
7
= 0.7 m
10
Position vector r⃗ = (0.5ı̂ + 0.7ȷ̂)m
|r⃗ | = �0.52 + 0.72 = √0.25 + 0.49 = √0.74 = 0.860 m
KFUPM-Physics Department
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