Physics 3A: Basic Physics I
Quiz #1c : Solutions
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Ax
๎
Acos
๎๎๎๎
๎
Ay
๎
Asin
๎๎๎๎๎
A
๎๎๎ ๎
Ax2
๎
Ay2
๎
๎
๎
tan
๎
1
๎
Ay
Ax
๎
A = Ax i + Ay j + Az k A * B = |A| |B| cos(ฮธ) A x B = |A| |B| sin(ฮธ)
A * B = AxBx + AyBy + AzBz A x B = (AyBz โ AzBy)i + (AzBx โ AxBz)j + (AxBy - AyBx )k
1. (2 pts) Suppose that two quantities W and V have different dimensions. Which of the
following operations could result in a meaningful physical results (circle the letter of
your answer)?
a.) W * V
b.) W3 / V2
c.) W - V
d.) W2 + V2
e.) both a. and b.
f.) both a. and d.
2. (2 pts) Given that V is a velocity, A is an acceleration, and S is a speed, which of the
following is a valid mathematical result (circle the letter of your answer)?
a.) A .
V
b.) A + V
c.) V x S
d.) V + S
e.) none of the above
3. (6 pts) Consider two vectors A = -5.7 i + 4.2 j and B = 3.33i + 6.67 j. Compute: a.)
A+B and give answer in unit vector notation and give the magnitude and direction. b)
do the same for A-B. (use back of sheet if necessary, circle your final answer and
show all work)
a.)
๎
A
๎๎๎
B
๎๎๎๎๎
5.7
๎
i
๎
4.2
๎
j
๎๎๎๎๎
3.33
๎
i
๎
6.67
๎
j
๎๎๎๎๎
2.4
๎
i
๎
10.9
๎
j
and
๎ ๎
A
"!
B
๎$#&% ')(
2.4
*
2
'
10.9
*
2
#๎+
5.8
119
#
11.17
#
11
and
