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**Unformatted text preview: **Answers (YELLOW test}I m da 1hr 1min — m
1105 points} a = 4 me’is dag) = —— = 5x10 5— = 4.7x10‘6 "g"
s dag 24 hr so min so 3 s?-
V
2] (10 pts} distance traveled = (ave speedﬂtime) or AX =‘Lgu—D-t or 0.05 Wt 3] {15 pts) a)LetT"1 represent one of the beams and-r'z the other ﬁ'
bg the Pythagorean theorem: [HI = [le = 5!? m “—_—
7.2 71 T": o'r‘z = (53:15» (5)(-5)+(5}(5) = 25 m2
also: 7’1 or} = [F1 I ﬁzlcosqa = [5f312cosqj = 1'5 costp rn2 -. coscp = 25275 = 13 or tp = cos"(1f3}= 70.50 b) (10 pts} Just make this a vector problem, as I did in class with mg "hike around a circular
path." Let ﬁbe the edge of the brace. From the diagram above: 7'2 =_r°1 + E or ﬁ' =‘r’2 —'r'1 = (5,-5,5) - (5,5,5) = (0,—10,o) or R = Iﬁ'l = 10 m 4] (10 pts} This is essentiallg the extra credit problem (which I also did in class).
At time =T the bug is at location :4 = U’zaT2 and moving at speed v = aT
Now the bug decelerates and its speed drops to 0: V v2 — v02 = 2a(x - x0) or 0 - (aTZl2 = 2(-a}(x - 1X2aT2} solve to get x = aT2 5] (20 pts} starting conditions: for No—No: x0 = 0 v0 = 10 ftfs a= 0
for Liberal: x0 = 30 ft 'v'g = 0 a = 2 ftx’s2
equation of motion f or No—No: x = 10t equation of motion for Liberal: >4 = 30 + t2
when they meet: XN = xL
or 10t = 30 + t2 solve to get: t = [10 1 J-20 11'2 = imaginarg => theg never meet, the Liberal is spared! 6] {15 pts each}
a)g = gg+vogt+1f2agt2 or 0
x= xo+voxt+1f2axt2 or' x 500 + 0 —1:"2gt2 solve to get t = 10 sec
0 +(15'130'1t1I + 0 = 1500 m b) vx = constant = 150 ms’s and v9 = v09 - gt = 0 -(9.EI}(10} = -98 mJ’s
therefore? 150? -98’j‘ mfs when bomb hits the ground Name- A SHOW YOUR WORK IF YOU WANT CREDIT
Here are some conversion factors: 1 inch = 2.540 cm; 12 inch = 1 foot; 1 mile = 5280 ft,- 100 cm = 1 meter; 1 slug = 14.59 kilograms; 211' radians = 360° = 1 rev; "9" = 9.8 mills2 = 32 fte's2 V1] The Japanese satellite Hagabusa is now in solar orbit and will rendezvous with an asteroid
named Itokawa. The satellite‘s ion engines can accelerate it at a = 4 meters per second per dag.
How does this compare to the acceleration "9" that you are used to? ' .. s l
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5W 1 W 4'94“ 65"“ 47C 9 f“ WW"— n M "why v, “mam”, . .ww.._m_‘___m_ 2] A bullet is fired completelg through a board that is 5 cm thick.
The bullet enters at speed 200 mfs and emerges at 100 mfs.
How long is the bullet in the board? D . . . . . . . . . . . . .. V 0. O§ I 0 + 200(S';>+ gl‘a(g. :: I00 0 05 61"” 2 is»
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’3 rallying at? 5] Republican Captain hip—No spots a libeggding 30 feet away who is trying
to register voters. Captain No-No wants to stop this and runs toward the liberal
at a constant 10 ftfsec. The liberal sees the danger
and flees on his solar—powered scooter which has an Vacceleration of only 2 ftISZ. What happens? m
Now» lye/2 2!”
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