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Unformatted text preview: PHY 2053, Section 3794, Fall 2009, Quiz 1
Use scientiﬁc notation and pay attention to signiﬁcant ﬁgures.
a) A rectangle has one side of 10.2-cm and one side which is 1-ft,2-in long. What is its
area in cm2 ?
1-ft,2-in = 14-in = 14 × 2.54-cm = 35.56-cm, so area = 35.56 × 10.2 = 362.712-cm2 . Note:
could truncate to 362.7-cm2 . Using scientiﬁc notation and keeping only 2 signiﬁcant ﬁgures
(14-in is only known to 2 signiﬁcant ﬁgures) gives area = 3.6 × 102 -cm2 .
b) You can spread oil paint over the surface at the rate of 0.046 cm2 /sec. How many
minutes does it take for you to cover the surface?
time = 362.7/0.046 sec = 7885. sec =7885/60 min = 1.3 × 102 -min (to 2 sig. ﬁgs). Note: use
your intermediate result from part a) with more than 2 sig. ﬁgs! 2.
a) The hypotenuse of a right-angled triangle has length 6.5-cm and one side is 6.0-cm long.
How long is the other side?
Using Pythagoras we have b = c2 − a2 = 6.52 − 6.02 cm = 2.5-cm. Note: only 2 sig. ﬁgs.
b) The sides of a right-angled triangle are 1.5-in, 2.0-in and 2.5-in. What is the tan of the
smallest angle inside the triangle?
The smallest angle is opposite the smallest side. The longest side is the hypotenuse, so tan
of the smallest angle is 1.5/2.0 = 0.75 = 7.5 × 10−1 in scientiﬁc notation. Note: tan is
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This note was uploaded on 12/15/2011 for the course PHY 2053 taught by Professor Buchler during the Fall '06 term at University of Florida.
- Fall '06