yoon (jy4326) – HW02 – markert – (58840)
1
This printout should have 19 questions.
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beFore answering.
001
10.0 points
IF the acceleration oF an object is zero at some
instant in time, what can be said about its
velocity at that time?
1.
It is positive.
2.
Unable to determine.
3.
It is not changing at that time.
correct
4.
It is zero.
5.
It is negative.
Explanation:
Solution:
By defnition, the acceleration
a
=
Δ
v
Δ
t
.
Since the acceleration is zero,
0 =
Δ
v
Δ
t
Δ
v
= 0
.
002
10.0 points
An object travels 5 m in the frst second oF
travel, 5 m again during the second second oF
travel, and 5 m again during the third second.
What is the approximate average accelera
tion oF the object during this time interval?
1.
3 m/s
2
2.
9 m/s
2
3.
4 m/s
2
4.
6 m/s
2
5.
8 m/s
2
6.
Unable to determine.
7.
7 m/s
2
8.
0 m/s
2
correct
9.
5 m/s
2
Explanation:
Solution:
Because the distance traveled each second
is constant, its velocity is constant. ThereFore,
the acceleration oF the object is zero.
003
10.0 points
A record oF travel along a straight path is as
Follows:
(a) Start From rest with constant accelera
tion oF 3
.
38 m
/
s
2
For 12
.
8 s;
(b)
Constant
velocity
For
the
next
0
.
977 min;
(c) Constant negative acceleration oF
−
9
.
1 m
/
s
2
For 5
.
77 s.
What was the total displacement
x
For the
complete trip?
Correct answer: 2911
.
18 m.
Explanation:
This trip is divided into three sections:
(a) Acceleration From rest:
x
a
=
1
2
at
2
(b) Constant velocity motion:
x
b
=
vt
(c) Deceleration:
x
=
vt
+
1
2
at
2
004
10.0 points
A 500kilogram sports car accelerates uni
Formly From rest, reaching a speed oF 30 me
ters per second in 6 seconds.
During the 6 seconds, the car has traveled
a distance oF
1.
90 m
correct
2.
15 m
3.
60 m
4.
30 m
5.
180 m
Explanation:
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2
v
f
=
v
0
+
a t
=
a t
since
v
0
= 0, so
a
=
v
f
t
.
s
=
s
0
t
+
v
0
t
+
1
2
a t
2
=
1
2
a t
2
=
1
2
p
v
f
t
P
t
2
=
1
2
v
f
t
since
v
0
= 0 and
s
0
= 0, so
s
=
1
2
(30 m
/
s) (6 s)
=
90 m
.
005
10.0 points
An electron, starting from rest and moving
with a constant acceleration, travels 4
.
5 cm in
1
.
8 ms.
What is the magnitude of this acceleration
in km/s
2
?
Correct answer: 27
.
7778 km
/
s
2
.
Explanation:
An electron starting from rest with con
stant acceleration will travel a distance of
d
=
1
2
at
2
in t seconds. Given the time and distance
traveled we solve for
a
:
a
=
2
d
t
2
making any necessary unit conversions along
the way.
006
(part 1 of 2) 10.0 points
The initial speed of a body is 6
.
58 m
/
s.
What is its speed after 3
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 Fall '09
 BOCKNACK
 Organic chemistry, Acceleration, Velocity, Correct Answer, m/s, Yoon

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