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Version 033 – Quiz 1 – gentle – (56245)
1
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001
10.0 points
Consider three Force vectors
v
F
1
with magni
tude 47 N and direction 120
◦
,
v
F
2
with mag
nitude 38 N and direction

150
◦
,
and
v
F
3
with magnitude 15 N and direction 140
◦
. All
direction angles
θ
are measured From the pos
itive
x
axis: counterclockwise For
θ >
0 and
clockwise For
θ <
0.
What is the magnitude oF the resultant vec
tor
v
F
=
v
F
1
+
v
F
2
+
v
F
3
?
1. 56.2016
2. 29.5698
3. 98.9936
4. 67.9336
5. 58.7614
6. 44.7903
7. 22.6656
8. 2.79696
9. 22.0693
10. 74.7855
Correct answer: 74
.
7855 N.
Explanation:
Let :
F
1
= 47 N
at
θ
1
= 120
◦
,
F
2
= 38 N
at
θ
2
=

150
◦
,
and
F
3
= 15 N
at
θ
3
= 140
◦
.
Each Force vector is defned by components
F
x
=
F
cos
θ
and
F
y
=
F
sin
θ ,
so the net
Force is defned by
F
x
=
F
1
,x
+
F
2
,x
+
F
3
,x
= (47 N) cos120
◦
+ (38 N) cos(

150
◦
)
+ (15 N) cos140
◦
=

67
.
8996 N
and
F
y
=
F
1
,y
+
F
2
,y
+
F
3
,y
= (47 N) sin120
◦
+ (38 N) sin(

150
◦
)
+ (15 N) sin140
◦
= 31
.
345 N
with magnitude
F
=
r
F
2
x
+
F
2
y
=
r
(

67
.
8996 N)
2
+ (31
.
345 N)
2
=
74
.
7855 N
.
002
10.0 points
A basketball player achieves a hang time oF
0
.
586 s in dunking the ball.
What vertical height will he attain? The
acceleration oF gravity is 9
.
8 m
/
s
2
.
1. 1.1982
2. 1.4025
3. 0.396607
4. 0.591706
5. 1.2996
6. 1.17889
7. 1.05495
8. 0.42066
9. 0.378692
10. 1.5642
Correct answer: 0
.
42066 m.
Explanation:
Let :
t
= 0
.
586 s
and
g
= 9
.
8 m
/
s
2
.
It takes the basketball player Δ
t
=
t
2
to
rise to his maximum height, defned by
h
=
1
2
g
(Δ
t
)
2
=
g
2
t
2
4
=
g t
2
8
=
(9
.
8 m
/
s
2
) (0
.
586 s)
2
8
=
0
.
42066 m
.
003 (part 1 of 2) 10.0 points
A car initially at rest on a straight road
accelerates according to the
acceleration vs
time
plot.
t
a
t
1
t
2
t
3
t
4
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View Full DocumentVersion 033 – Quiz 1 – gentle – (56245)
2
What is the best description of the motion
of the car? Take forward to be the positive
direction.
1.
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 Fall '07
 Swinney
 mechanics, Force

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