1. Ib lub log uas muaj 3 0 cm hauv lub vojvoog tig ntawm qhov tsis hloov pauv 5 rad/s 2. Qhov loj ntawm qhov kev nrawm ntawm ib qho chaw nyob ntawm (a) 10 cm ntawm qhov chaw nruab nrab (b) 20 cm ntawm qhov chaw nruab nrab (c) ntawm ntug ntawm lub log yog dab tsi?
Paub:
Lub vojvoog (r) = 30 cm = 0.3 m
Kev nrawm ntawm lub kaum sab xis ( α ) = 5 rad/s 2
Xav tau: kev nrawm linear (a) r = 0.1 m (b) r = 0.2 m (c) r = 0.3 m
Tshuaj:
Kev sib raug zoo ntawm kev nrawm linear (a) thiab kev nrawm angular:
a = r α
(a) kev nrawm nrawm, r = 0.1 m
a = (0.1 m)(5 rad/s2 ) = 0.5 m/ s2
(b) kev nrawm nrawm, r = 0.2 m
a = (0.2 m)(5 rad/s2 ) = 1 m/ s2
(c) kev nrawm nrawm, r = 0.3 m
a = (0.3 m)(5 rad/s2 ) = 1.5 m/ s2
[irp]
2. Ib lub pulley uas muaj lub vojvoog 50 cm. Yog tias qhov kev nrawm ntawm ib qho chaw nyob ntawm ntug ntawm lub pulley yog 2 m/s 2 , txiav txim siab qhov kev nrawm ntawm lub pulley!
Paub:
Lub vojvoog (r) = 50 cm = 0,5 m
kev nrawm nrawm (a) = 2 m/s 2
Xav tau: qhov kev nrawm ntawm lub kaum sab xis
Tshuaj:
α = a / r = 2 / 0.5 = 4 rad/s 2
3. Cov hniav hauv lub tshuab sib tov muaj 20 cm hauv lub vojvoog, thaum pib so. Tom qab 2 vib nas this, cov hniav tig 10 rad/s. Txheeb xyuas qhov loj ntawm kev nrawm linear (a) ib qho chaw nyob ntawm 10 cm ntawm qhov chaw nruab nrab (b) ib qho chaw nyob ntawm ntug ntawm cov hniav.
Paub:
Lub vojvoog (r) = 20 cm = 0.2 m
Qhov pib ntawm lub kaum sab xis ( ωo ) = 0
Qhov kawg angular velocity ( ω t ) = 10 radians/ob
Lub sijhawm luv (t) = 2 vib nas this
Xav tau: qhov kev nrawm linear ntawm ib qho chaw nyob ntawm (a) r = 0.1 m (b) r = 0.2 m
Tshuaj:
ω t = ω o + α t
10 = 0 + α (2)
10 = 2 α
α = 10 / 2
α = 5 rad/s
(a) kev nrawm nrawm ntawm r = 0.1 m
a = r α = (0.1 m)(5 rad/s 2 ) = 0.5 m/s 2
(b) kev nrawm nrawm ntawm r = 0.2 m
a = r α = (0.2 m)(5 rad/s 2 ) = 1 m/s 2
[irp]
4. Ib lub log uas muaj 20 cm radius raug nrawm rau 2 vib nas this los ntawm 20 rad/s kom so. Txheeb xyuas qhov loj ntawm kev nrawm linear (a) ib qho chaw nyob ntawm 10 cm ntawm qhov chaw nruab nrab (b) ib qho chaw nyob ntawm 10 cm ntawm qhov chaw nruab nrab.
Paub:
Lub vojvoog (r) = 20 cm = 0.2 m
Qhov pib ceev ntawm lub kaum sab xis ( ωo) = 20 rad/s
Qhov ceev kawg ntawm lub kaum sab xis ( ωt ) = 0
Lub sijhawm luv (t) = 2 vib nas this
Xav tau: Qhov kev nrawm linear (a) r = 0.1 m (b) r = 0.2 m
Tshuaj:
ω t = ω o + α t
0 = 20 + α (2)
-20 = 2 α
α = -20 / 2
α = -10 rad/s
Lub cim tsis zoo txhais tau tias qhov ceev ntawm lub kaum sab xis txo qis.
(a) kev nrawm nrawm ntawm r = 0.1 m
a = r α = (0.1 m)(-10 rad/s 2 ) = -1 m/s 2
(b) kev nrawm nrawm ntawm r = 0.2 m
a = r α = (0.2 m)(-10 rad/s 2 ) = -2 m/s 2
[irp]
[wpdm_package id='429′]
[wpdm_package id='439′]
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