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Ch1H2 – florin – (56950)
1
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001 (part 1 of 7) 3.0 points
A spacecraft is observed to be at location
h200 m, 300 m, −400 mO relative to an origin
located on a nearby asteroid, and 5 s later it
is observed to be at location h475 m, 100 m,
−650 mO . Find the average velocity of the
spacecraft, v¯ = hv
x
, v
y
, v
z
O .
What is v
x
in m/s?
Correct answer:
55 m/s.
Explanation:
The average velocity of the spacecraft
is calculated by finding the change of
position over a change in time:
v¯ =
~r
f
−
~r
i
.
t
Because
~r is
a
vector,
the
average
velocity will also be a vector and each
component must be calculated separately.
For v¯
x
the value becomes:
v¯
x
=
v
2
x
−
v
1
x
t
=
(475
m) − (200
m) (5 s)
=
55 m/s
3
(part 2 of 7) 3.0 points
What is v
y
in m/s?
Correct answer:
−40 m/s.
Explanation:
The average velocity of the spacecraft
is calculated by finding the change of
position over a change in time:
v¯ =
~r
f
−
~r
i
.
t
Because
~r is
a
vector,
the
average
velocity will also be a vector and each
component must be calculated separately.
For v¯
y
the value becomes:
v¯
y
=
v
2
y
−
v
1
y
t
=
(100
m) − (300
m) (5 s)
=
−40 m/s
4
(part 3 of 7) 3.0 points
What is v
z
in m/s?
Correct answer:
−50 m/s.
Explanation:
The average velocity of the spacecraft
is calculated by finding the change of
position over a change in time:
v¯ =
~r
f
−
~r
i
.
t
Because
~r is
a
vector,
the
average
velocity will also be a vector and each
component must be calculated separately.
For v¯
z
the value becomes:
v¯
z
=
v
2
z
−
v
1
z
t
=
(−650 m) − (−400 m)
(5 s)
=
−50 m/s
5
(part 4 of 7) 2.0 points
What is ~v in m/s?
Correct answer:
84.4097 m/s.
Explanation:
The magnitude is calculated by:
q
~v =
v
x
2
+ v
y
2
+ v
z
2
q
=
(55 m/s)
2
+ (−40 m/s)
2
+ (−50 m/s)
2
=
84.4097 m/s
5
(part 5 of 7) 3.0 points
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View Full DocumentCh1H2 – florin – (56950)
2
Find
the
unit
vector
in
the
direction
of
the
For example:
velocity of the spacecraft, vˆ = hvˆ
x
, vˆ
y
, vˆ
z
O .
vˆ
z
=
v
z
What is vˆ
x
?
~v
=
−50 m/s
Correct answer:
0.651584.
84.4097 m/s
Explanation:
=
−0.592349
The unit vector for a vector is given as :
hv
x
, v
y
, v
z
O
008 (part 1 of 7) 3.0 points
vˆ = hvˆ
x
, vˆ
y
, vˆ
z
O =
Here
are
the
positions
at
three
di
f
erent
~v
times for a bee in flight (a bee’s top speed is
For example:
about 7m/s .
vˆ
x
=
v
x
T ime
P osition
~v
9.5 s
h−2.5 m, 10.4 m, 0 mO
55 m/s
10 s
h−0.3 m, 7.2 m, 0 mO
=
84
.4097 m/s
10.5 s
h1.5 m, 2.7 m, 0 mO
=
0.651584
Between 9.5 s and 10 s, find the bee’s aver
006 (part 6 of 7) 3.0 points
age velocity:
A
A
A
What is vˆ
y
?
v¯
= hv
x
, v
y
, 0O .
Correct answer:
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 Spring '08
 Turner

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