# 2010 AP Free Response Solution

```2O1O APC
PHYSICS B FREE-RESPONSE OT'ESTIONS (FOrM B)
F_0.020 m_---l
ml
J. (15
m2
(,tCC \0
l-T = q\&t(o
f E'
points)
{
l\alic
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m r e rrll.
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by a 0.020 m length of insulating string as
Two small objects, each with a chafge of '*
shown in the diagram above. The q[i_ects are in)-tially at rest on a horizontal, nonconductins frictionless surfag
TheeffectoforavitvoneachobiecMrebtheotherisneclieible.|r:-.t\ir..,i\"Y4.
(b) Illustrate the electric field by drawing electric field lines for the two objects on the following diagram..
+ry
"ffi;
'H-,*.*,
,,(iF
5l
_i .1, L aqp4
The masses of the objects are
1W*^^"
J
ml = 0.030 kg and mz = 0.060kg. The string is now
r^tgf
c Y\sn'
cut.
d '
i(c),/Calculate the magnitude of the initial acceleration of each object'
(d) On
v
the axes below, qualitatively sketch a graph of the acceleration a of the object of mass m2 versus the
distance d between the objects
"o"t
F=*o..-a ^
i,(
ffir'. a,kxl0'=,031
T'
o.=\,2*i6r*lt' I \
,/
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rrnz:3'ioet0-=-Obq r2l i
o*T;.;s'
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ta< o'I-"
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e*3at stosY -lAnAs
F:r-.r.
Y=r\^G\
a:k.ox\(r3am\s'l\ L
k:Ct)l
o0?"Yn
happens to the speeds of the objects as time increases, assuming that the objects
remain on the horizontal, nonconducting frictionless surface.
(e) Describe qualitatively what
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S,3lrt-d t-l*lf
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s^.\t\
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CF=a+
^
@ 2010
The College Board.
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```

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