1. Ib lub pob, txuas rau qhov kawg ntawm txoj hlua kab rov tav, tig mus rau hauv ib lub voj voog uas muaj radius 20 cm. Lub pob ncig 360o txhua ob. Txheeb xyuas qhov loj ntawm kev nrawm ntawm centripetal!
Paub:
Qhov ceev ntawm lub kaum sab xis (ω)= 360 TZSo/ob vib nas this = 1 revolution/ob vib nas this = 6.28 radians/ob vib nas this
Lub vojvoog (r) = 20 cm = 0.2 m
Xav tau: Kev nrawm ntawm lub centripetal (a)r)
Tshuaj:
ar = v2 / r ib —> v = r ω
ar = (r ω)2 / r = r2 ω2 / r ib
ar =r ω2
as = kev nrawm ntawm lub centripetal, v = linear velocity, r = radius, ω = angular tshaj tawm
Lub magnitude ntawm centripetal acceleration :
ar =r ω2 ar = (0,2 m)(6.28 rad/s)
ar = 1.256 m/s2
2. Lub log uas muaj 30 cm radius tig nrog lub zog 180 rpm. Txheeb xyuas qhov kev nrawm ntawm lub centripetal ntawm ib qho chaw ntawm ntug ntawm lub log!
Paub:
Lub vojvoog (r) = 30 cm = 0.3 m
Qhov ceev ntawm lub kaum sab xis (ω) = 180 lub voj voog / 60 vib nas this = 3 lub voj voog / vib nas this = (3) (6.28 radians) / vib nas this = 18.84 radians / vib nas this
Xav tau: kev nrawm ntawm centripetal (ar) ntawm r = 0.3 m
Tshuaj:
Qhov loj ntawm centripetal acceleration:
ar =r ω2
ar = (0.3 m)(18.84 rad/s)
ar = 5.65 m/s2
3. Lub tsheb sib tw khiav ntawm txoj kev voj voog uas muaj vojvoog 50 meters. Yog tias lub tsheb khiav ceev 72 km/h, txiav txim siab qhov loj ntawm qhov kev nrawm ntawm lub centripetal!
Paub:
Lub vojvoog (r) = 50 meters
Ceev (v) = 72 km/h = (72)(1000 meters) / 3600 vib nas this = 20 meters/ vib nas this
xav : qhov loj ntawm qhov kev nrawm ntawm centripetal (ar)
Tshuaj:
ar = v2 / r = 202 / 50 = 400 / 50 = 8 m/s2
4. Lub tsheb muaj qhov siab tshaj plaws ntawm centripetal acceleration ntawm 10 m/s2, yog li lub tsheb tuaj yeem tig tau yam tsis plam tawm ntawm txoj kev nkhaus. Yog tias lub tsheb txav mus tas li ntawm 108 km/h, lub vojvoog ntawm txoj kev nkhaus tsis muaj ntug yog dab tsi?
Paub:
Kev nrawm ntawm centripetal (ar) = 10 m/s2
Qhov ceev ntawm lub tsheb (v) = 108 km/h = (108)(1000) / 3600 = 30 meterss/second
Xav tau: vojvoog (r)
Tshuaj:
r = v2 / ibr
r = 302 / 10 = 900 / 10 = 90 meterss
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