Phys 113 Problem Set 1 Solutions
1)
90 km
h
1000 m
25 m s
h
3600 s
km
c
v
==
,
750 km
h
1000 m
20.83 m s
h
3600 s
km
t
v
()
25 m s
cc
x
vt
t
,
( )
0
100 m
20.83 m s
tt
t
x
xv
t
=+=
+
t
ct
x
c
=
,
25 m s
100 m
20.83 m s
=+
,
( )
4.16 m s
100 m
t
=
,
24 s
0.4 min
t
2)
No, a change in speed would indicate a change in the magnitude of velocity.
Yes, the object could be changing directions while moving at a constant speed.
Yes, speed is just the magnitude, which is always positive, of the velocity.
No, speed is just the magnitude, which is always positive, of the velocity.
3)
(a)
2
2
2.0 m
4.6 m s
1.1 m s
x
=−
+
(
)
2
2
1
2.0 m
4.6 m s
1.0 s
1.1 m s
1.0 s
1.5 m
x
+
=
−
(
)
( )
2
2
2
2.0 m
4.6 m s
2.0 s
1.1 m s
2.0 s
2.8 m
x
+
=
−
(
)
( )
2
2
2
2.0 m
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 Spring '08
 Jordan
 Velocity

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