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Physics 111.01
Fall, 2008
Solutions, Problem Set 1b (1)
HW 1b # 1 = Walker3 1.
.P.02.
A human hair has a thickness of about [68]
μ
m.
(a)
What is this in meters?
This is a problem in conversion of units.
The method is to multiply by a fraction which is
equal to 1, since it represents a ratio of two equal things.
6
10 m
68
m
68E
6 m=6.8E5 m
m
−
=−
(b)
What is this in km?
We just continue on converting.
3
1 km
6.8E5 m
6.8 E8 m
10 m
=
HW 1b # 2 = Walker3 1.P.04
A particular computer can do [263.2] megacalculations
per second.
How many calculations can it do in a nanosecond?
Here we use the intuitive relation number = rate times time:
()
calculations
number = rate * time = 263.2E6
1E
9 sec
0.263 calculations
sec
⎛⎞
−=
⎜⎟
⎝⎠
This is a bit of a funny answer, since a computer can't really do a fraction of a calculation.
It presumably means that in about 4 nanoseconds the computer will do a single
calculation.
HW 1b # 3 = Walker3 1.P.02
1
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This note was uploaded on 05/13/2010 for the course PHYSICS 111 taught by Professor Staff during the Fall '08 term at S.F. State.
 Fall '08
 Staff
 Physics

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