1. Ib yam khoom muaj lub zog inertia ntawm 1 kg m2 tig ntawm qhov ceev ntawm 2 rad/s. Lub zog kinetic ntawm yam khoom yog dab tsi ?
Paub:
Lub sijhawm ntawm inertia ( I) = 1 kg m2
Qhov ceev ntawm lub kaum sab xis ( ω) = 2 rad/s
Xav tau: Lub zog kinetic ntawm kev sib hloov ( KE )
Tshuaj:
Cov mis ntawm lub zog kinetic tig:
KE = 1/2 I ω 2
KE = lub zog kinetic ntawm kev sib hloov (kg/m²)2/s2), Kuv = lub sijhawm ntawm inertia (kg/m²)2), ω = qhov ceev ntawm lub kaum sab xis (rad/s)
Lub zog kinetic ntawm kev sib hloov:
KE = 1/2 I ω 2 = 1/2 (1)(2) 2 = 1/2 (1)(4) = 2 Joules
[irp]
2. Ib lub log uas hnyav 20-kg uas muaj lub vojvoog ntawm 0.2 m tig ntawm qhov ceev ntawm lub kaum sab xis tas li ntawm 4 rad/s. Lub zog kinetic ntawm lub log yog dab tsi?
Paub:
Qhov hnyav ntawm lub tog raj kheej pulley (m) = 20 k g
Lub vojvoog ntawm lub tog raj kheej (r) = 0.2 m
Qhov ceev ntawm lub kaum sab xis (ω) = 4 ra d/s
Xav tau: Lub zog kinetic rotational yog dab tsi
Kev daws teeb meem;
Cov mis ntawm lub sijhawm ntawm inertia ntawm lub tog raj kheej:
Kuv = 1/2 m2
Kuv = lub sijhawm ntawm inertia ( kg m2 ) , m = pawg (kg), r = radius (meters)
Lub sijhawm ntawm inertia ntawm lub tog raj kheej pulley:
Kuv = 1/2 (20)(0.2) 2 = (10)(0.04) = 0.4 kg m2
Lub zog kinetic ntawm lub pulley:
KE = 1/2 I ω 2 = 1/2 (0.4)(4) 2 = (0.2)(16) = 3.2 Joules
[irp]
3. A- lub pob hnyav 10 kg uas muaj lub vojvoog ntawm 0.1 m tig ntawm qhov tsis hloov pauv ntawm 10 rad/s. Lub zog kinetic ntawm lub pob yog dab tsi.
Paub:
Qhov hnyav ntawm lub pob (m) = 10 kg
Lub vojvoog ntawm lub pob (r) = 0.1 m
Qhov ceev ntawm lub kaum sab xis (ω) = 10 r ad/s
Xav tau: Lub zog kinetic ntawm kev sib hloov
Tshuaj:
Cov mis ntawm lub sijhawm ntawm inertia:
Kuv = (2/5) mr 2
Kuv = lub sijhawm ntawm inertia (kg m2 ) , m = pawg (kg), r = radius (m)
Lub sijhawm ntawm inertia ntawm lub pob:
Kuv = (2/5)(10)(0.1) 2 = (4)(0.01) = 0.04 kg m2
Lub zog kinetic ntawm lub pob:
K E = 1/2 I ω 2 = 1/2 (0.04)(10) 2 = (0.02)(100) = 2 Joules
[irp]
4. Ib lub khoom me me uas hnyav 0.5- kg tig nrog lub kaum sab xis tas li ntawm 2 rad/s. Lub zog kinetic ntawm lub khoom me me yog dab tsi yog tias lub vojvoog radius ntawm lub voj voog yog 10 cm.
Paub:
Qhov hnyav ntawm cov khoom me me (m) = 0.5 k g
Lub vojvoog ntawm lub pob (r) = 10 cm = 10/100 = 0.1 m
Qhov ceev ntawm lub kaum sab xis (ω) = 2 rad/ s
Xav tau: Lub zog kinetic ntawm kev sib hloov
Tshuaj:
Lub sijhawm ntawm inertia rau cov khoom me me:
Kuv = mr 2 = (0.5)(0.1) 2 = (0.5)(0.01) = 0.005 kg m 2
Lub zog kinetic ntawm kev sib hloov:
K E = 1/2 I ω 2 = 1/2 (0.005)(2) 2 = 1/2 (0.005)(4) = (0.005)(2) = 0.01 Joule
