Physics 101
Classical Physics
Spring 2010
Quiz 2
Instructions
: The answer sheets must be handed in as soon as time is called. You have until
9:20am.
Answer the following two multiple choice questions. Each question is worth 5 points.
1.
Vector
vector
A
= 2
ˆ
i

3
ˆ
j
, and vector
vector
B
=

1
ˆ
i
+ 4
ˆ
j
. If
vector
C
=
vector
A
+
vector
B
, what is

vector
C

?
(a) 4, (b)
√
13 +
√
5
, (c)
√
2
, (d)
√
58
, (e)
√
10
We need to first add the vector components to get
vector
C
:
vector
C
= (2

1)
ˆ
i
+ (

3 + 4)
ˆ
j
= 1
ˆ
i
+ 1
ˆ
j
To get the magnitude, we use the Pythagorean theorem:

vector
C

=
√
1
2
+ 1
2
=
√
2
so the answer is
c
.
2.
The largest the sum of any two vectors can be is when:
(a) They point in the same direction
(b) They point in opposite directions
(c) They are at right angles to each other
(d) They have the same magnitude
(e) Depends on the magnitude of each vector
When vectors point in the same direction, their magnitudes add and therefore that is the
biggest the sum can be. So the answer is
a
.
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 Spring '09
 Physics, Equations, Pythagorean Theorem, Acceleration, Velocity, Highest point, 1 5M

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