8/7/2019 Bi tp c nng bo ton c nng

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H tn:

BI TPLP 10T1

C NNG - BO TON C NNG(RI T DO)

Ngy19/02/2011

1 Mt vt nng 3 kg c th ri t do t cao 45 m. Tnh c nng ca vt vtr th v chm t.

2 Mt vt nng 4 kg c nm thng ng ln trn vi vn tc 30 m/s t cao30 m. Tnh c nng ca vt v tr nm v khi chm t. Xem lc cn khng khl khng ng k.

3 Mt vt nng 2 kg c nm thng xung di vi vn tc 10 m/s t cao 30m. Tnh c nng ca vt v tr nm v khi chm t. Xem lc cn khng kh lkhng ng k.

4 Mt vt nng 2 kg c nm thng xung di vi vn tc 5 m/s. C nng cavt lc l 325 J. Hi cao nm vt l bao nhiu? Xem lc cn khng kh lkhng ng k.

5 Mt vt nng 4 kg c th ri t do, khi chm t t, ng nng ca vt l 300J. Hi cao th vt l bao nhiu?

6 Mt vt c nm ln cao vi vn tc 4 m/s t cao 30 m. Khi chm t vt cng nng l 800 J. Hi khi lng ca vt l bao nhiu?

7 Mt vt nng 4 kg c th ri t do t cao 45 m.a. Tnh c nng ca vt.b. Tnh th nng ca vt cao 28 m.c. Tnh ng nng ca vt cao 28 m. T suy ra vn tc ca vt lc .

8 Mt vt nng 3 kg c th ri t do t cao 25 m.a. Tnh c nng ca vt.b. Tnh ng nng ca vt khi vt t vn tc 15 m/s.c. Tnh th nng khi vt t vn tc 15 m/s. T suy ra cao ca vt lc .

9 Mt vt nng 5 kg c th ri t do t cao 105 m.a. Tnh ng nng v th nng ca vt sau khi chuyn ng c 2 s.b. Tnh ng nng ca vt khi chm t. T suy ra ln vn tc chm t.

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8/7/2019 Bi tp c nng bo ton c nng

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10 Mt vt nng 4 kg c nm thng ng xung di vi vn tc 10 m/s tcao 105 m. Xem lc cn khng kh l khng ng k.a. ng nng ca vt sau 1 s chuyn ng l bao nhiu? Khi vt ang

cao no?b. ng nng ca vt khi chm t l bao nhiu? T suy ra ln vn tc

chm t.

11 Mt vt nng 2 kg c nm thng ng ln cao vi vn tc 26 m/s t cao 30m. Xem lc cn khng kh l khng ng k.a. Khi vt ln n cao nht, th nng ca n l bao nhiu? Vt cao no?b. Tnh vn tc chm t ca vt.

12 Mt vt nng 3 kg c th ri t do t cao 60 m. cao no, ng nngbng th nng?

13 Mt vt nng 2 kg c nm thng ng xung di vi vn tc 5 m/s t cao50 m. cao no, ng nng bng 2 ln th nng?

14 Mt vt nng 2,5 kg c nm ln cao vi vn tc 30 m/s t cao 10 m. Khivt c th nng bng 3 ln ng nng, vn tc ca vt l bao nhiu?

15 Mt vt nng 4 kg c th ri t do t cao 45 m. Cho g = 10 m/s2.a. Tnh c nng ca vt ti v tr th v v tr chm t.b. Tnh vn tc ca vt cao 32 m.c. Khi vt c vn tc 21 m/s, vt ang cao no?d. cao no th ng nng bng 1/2 th nng?

16 Mt vt nng c nm ln cao vi vn tc 10 m/s t cao 45 m. Khi chmt, ng nng ca vt l 1200 J.a. Tm khi lng ca vt?b. cao no, ng nng bng 2 ln th nng?c. cao no, vn tc bng 1/2 vn tc lc chm t?

17 Mt vt khi lng 5 kg c th ri t do t cao 105 m.a. cao no, ng nng v th nng bng nhau?b. cao no, th nng bng 2 ln ng nng?c. Khi ng nng bng 1/4 th nng th vn tc l bao nhiu?

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