111 lines
1.5 KiB
Plaintext
111 lines
1.5 KiB
Plaintext
pr1
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jaka je uhlova rychlost bodu hovnomerne se otacejicicho kola auta
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o prumeru 60cm jedely auto rychosti 90km/h? S jako frequenci se kolo otaci
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kolik otacek ta min kolo vikona?
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r = 0.3
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v/r = ω
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ω = 83.33 s⁻¹
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ω = 2pi*f
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{f} = 83.3/2pi
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1. 13.3Hz
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2. 798ot za mine
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vypočtete delku oblouku ktery opise konovi bod delsi rucicky dlouhe 10cm velkych
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hodin, uplineli 20min
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r = 0.1m
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t = 20min = 1/3h
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l = 1/3 * 2pi*r
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l = 0.21m
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Remenice elektromotoru ma polomer 3cm a pohani remenovim pohonem kolo o polomeru 15cm. S jakou frequenci se otaci toto kolo jely frekvence elektromotoru 50Hz?
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r = 0.003
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f = 50Hz
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f₂/f₁ = r₁/r₂
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f = 10Hz
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vypoctete uhlovou rychlost otaceni zemne a rychlost s jakou se pohybuji
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body na rovniku
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ω = 2pi/T
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{ω} = 2pi/24*3600
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ω = 7,3*10⁻⁵
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v = 6378 *10⁻³ * 7.3*10⁻⁵
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v = 466 m/s
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Zrychleni pohybu po kruznici
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zrychleni zmena rychlosti za caš
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v₁ = v₂
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→
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v meni zrychleni
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→
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aˇd = v²/r = ω²*r
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pr1
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pracka ma rychlost otacek 1000 oacek Za min
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a) frekvence otaceni
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f = 1000/60 = 17Hz
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b) velikost dostrediveho zrychleni, jeli prumer 40cm
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a = ω²r = (2pi*f)² * r = 4pi²f²r
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a = 2193
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auto projizdi zatackou o polomeru 100m rychlosti 72km/h vypočete jeho do stredive zrychleni
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v = 20m/s
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r = 100m
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a = 400/100 = 4m*s⁻²
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zeme kolem
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slunce
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v = 3*10⁴
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{a} = 3*10⁴/149,6*10
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pr
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za jako dobu pri volnem padu okamzite rychlosti z 10m/s na 30m/s
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jako drahu urazi
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20 = 10 * t
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2s = t
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a) 2s
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b)
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1/2 * 10 * 4 + 10 * 2
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40m
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