01prob_10

01prob_10 - Assigment#1 Page 1 of 3 UC Davis Physics 9A...

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Unformatted text preview: Assigment #1, 4/1/10 Page 1 of 3 UC Davis Physics 9A Assignment #1 Cole [1.3] 

The
speed
of
light
is
3
ª
10 8 
m/s.

It
takes
light

 t = d v = 1 ft ( ) 0.305 m/ft ( ) 3 × 10 8 m/s = 1.0 ns 
to
travel
 one
foot. [1.8] 
 180,000 fl / fn = 180,000 fl / fn 1/8 mi/ fl 14 D/ fn × 24 hr/D 
=
67
mi/hr. [1.12] 


 t 
=
(365.24
D/yr)(24
hr/D)(3600
s/hr)
=
3.1557
ª
10 7 
s.

 e = true value-approx value true value × 100% 

õ

 e = 3.1557 − 3.1416 3.1557 × 100% 
=
0.4
% [1.19] 
Let's
estimate
how
many
sheets
there
might
be.

A
ream
(500
sheets)
of
paper
is
about
2
in
 thick.

From
the
dimensions
of
the
box
there
must
be
two
stacks
of
paper
9
in
thick
í
10
in

õ
10
 reams

=
5000
pieces
of
paper
so
we
are
within
a
factor
of
2
of
10,000
for
our
guess.

Hence
it
 must
be
10,000
of
light
weight
paper
and
certainly
not
a
million. [1.28] 

A
ream
(500
sheets)
of
paper
is
about
2
in
thick.

Estimate
that
a
$500
stack
would
be
 about
5
cm
thick.

õ

$500
ª20/m
=

$10,000/m.

The
moon
is
4
ª
10 8 
m
away

õ

 ($10 4 /m)(4
ª
10 8 m)=
$4
ª
10 12 

=

4
T$

=
4
(terabucks).

The
cost
of
building
a
spaceship
and
 sending
it
could
well
cost
several
billion
dollars
of
today's
money,
but
this
is
still
well
below
a
 trillion
dollars. [1.41] 

The
total
displacement
is
the
sum
of
the
individual
displacements:

Î r√
=
Îr√ 1 
+
Îr√ 2 
+
Îr√ 3 
.

 Resolving
into
Cartesian
components
with
east
as
the
 x-direction
and
north
as
the
 y- direction, Δ r 1 = ˆ i + 3.25 ˆ j Δ r 2 = − 4.75 ˆ i + ˆ j Δ r 3 = ˆ i − 1.5 ˆ j Δ r = − 4.75 ˆ i + 1.75 ˆ j 

 Δ...
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This note was uploaded on 09/28/2011 for the course PHY 9A taught by Professor Svoboda during the Spring '08 term at UC Davis.

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01prob_10 - Assigment#1 Page 1 of 3 UC Davis Physics 9A...

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