Piv txwv ntawm cov lus nug txog lub zog kinetic thiab physics

5 Piv txwv ntawm lub zog kinetic thiab cov lus nug txog kev ua haujlwm physics

1. Lub tsheb uas hnyav 5000 kg thaum xub thawj nres, thiab tom qab ntawd txav mus rau qhov ceev ntawm 20 m/s. Txheeb xyuas tag nrho cov haujlwm ua tiav rau lub tsheb...
Kev Sib Tham
Nws yog paub :
Qhov hnyav (m) = 5000 kg
Qhov ceev pib (v_o) = 0 m/s (thawj zaug lub tsheb nres twj ywm)
Qhov ceev kawg (v_t) = 20 m/s
Nug Tag nrho cov kev siv zog
Jawb :
Kev tshawb fawb txog lub zog ua haujlwm-kinetic hais tias tag nrho cov haujlwm yog sib npaug rau qhov kev hloov pauv ntawm lub zog kinetic. Mathematically:
Tag nrho cov kev siv zog:
W_{tag nrho cov} = ½ m (v)_t² -v_o²)
W_{tag nrho cov} = ½ (5000)(20)² - 0²)
W_{tag nrho cov} = (2500)(400 – 0)
W_{tag nrho cov} = (2500)(400)
W_{tag nrho cov} = 1000.000
Tag nrho cov haujlwm yog 1000.000 Joules.

2. Ib yam khoom uas hnyav 10 kg thaum xub thawj txav mus nrog qhov ceev 5 m/s. Ib pliag tom qab ntawd, yam khoom txav mus nrog qhov ceev 10 m/s. Xam seb tag nrho cov haujlwm ua tiav rau yam khoom ntawd yog dab tsi.
Kev Sib Tham
Nws yog paub :
Qhov hnyav ntawm yam khoom (m) = 10 kg
Qhov ceev pib (v_o) = 5 m/s
Qhov ceev kawg (v_t) = 10 m/s
Nug : tag nrho cov kev siv zog
Jawb :
Tag nrho cov kev siv zog:
Tag nrho cov haujlwm yog 375 Joules.

3. Lub tsheb uas hnyav 2000 kg tab tom khiav ntawm qhov ceev ntawm 10 m/s. Tam sim ntawd, tus tsav tsheb txo qhov ceev ntawm lub tsheb mus rau 5 m/s. Txoj haujlwm uas tus tsav tsheb ua rau lub tsheb yog...
Kev Sib Tham
Nws yog paub :
Qhov hnyav ntawm lub tsheb (m) = 2000 kg
Qhov ceev pib (v_o) = 10 m/s
Qhov ceev kawg (v_t) = 5 m/s
Nug : tag nrho cov kev siv zog
Jawb :
Tag nrho cov kev siv zog:
Tag nrho cov haujlwm yog 75.000 Joules.
Ib lub cim tsis zoo txhais tau tias lub zog uas ua rau lub tsheb nyob rau sab nraud ntawm qhov kev hloov chaw ntawm lub tsheb. Kev ua haujlwm tsis zoo kuj txhais tau tias lub zog kinetic ntawm lub tsheb txo qis.

4. Lub tsheb uas hnyav 1 tuj thaum xub thawj nres. Ib pliag tom qab, nws txav mus rau qhov ceev ntawm 10 m/s. Qhov ntau ntawm cov haujlwm ua los ntawm lub cav ntawm lub tsheb yog...
A. 1.000 Joule
B. 10.500 Joule
C. 15.000 Joule
D. 25.000 Joule
E. 50.000 Joules
Kev Sib Tham:
Nws yog paub :
m = 1 tuj = 1000 kg, v_o = 0 m/s, v_t = 10 m/s
Nug :
Kev siv zog (W)?
Jawb :
Ua haujlwm = kev hloov pauv ntawm lub zog kinetic

Kev hloov pauv ntawm lub zog kinetic :
= ½ m(v)_t² -v_o²) = ½ (1000)(100 – 0) = ½ (1000)(100) = 50.000 kg m2²/s² = 50.000 Joule
Yog li ntawd W = 50.000 Joules
Cov lus teb yog yog E.

5. Ib lub rooj uas hnyav 10 kg thaum xub thawj nws nyob ruaj ruaj rau ntawm ib lub hauv pem teb du, ces nws raug thawb rau 10 vib nas this kom nws txav mus rau hauv ib txoj kab ncaj nraim nrog qhov nrawm ntawm 2 m/s.²Qhov loj ntawm kev siv zog uas tau tshwm sim yog ...
A. 2000 Joule
B. 3000 Joule
C. 6000 Joule
D. 8000 Joule
E. 9000 Joules
Kev Sib Tham:
Nws yog paub :
m = 10 kg, t = 10 vib nas this, v_o = 0, a = 2 m/s²nyob rau hauv_t =?
Nug :
Kev siv zog (W)?
Jawb :
Xam qhov ceev kawg (v_t):
v_t = v_o + ntawm = 0 + (2)(10) = 20 m/s

Ua haujlwm = kev hloov pauv ntawm lub zog kinetic

Kev hloov pauv ntawm lub zog kinetic :
= ½ m(v)_t² -v_o²) = ½ (10)(400 – 0) = ½ (10)(400) = ½ (4000) = 2000 Joules
Yog li ntawd W = 2000 Joules
Cov lus teb yog lawm yog A.