Công suất - Bài tập nâng cao

Home Lớp 10 Vật lý 10 - Sách kết nối tri thức Bài 24. Công suấtBài tập nâng cao

{"common":{"save":0,"post_id":"8649","level":3,"total":10,"point":10,"point_extra":0},"segment":[{"id":"7959","mon_id":"1158790","chapter_id":"1159772","post_id":"8649","question":"Mô\u0323t ô tô cha\u0323y \u0111ê\u0300u trên \u0111\u01b0\u01a1\u0300ng v\u01a1\u0301i vâ\u0323n tô\u0301c 72 km\/h. Công suâ\u0301t trung bi\u0300nh cu\u0309a \u0111ô\u0323ng c\u01a1 la\u0300 60 kW. Công cu\u0309a l\u01b0\u0323c pha\u0301t \u0111ô\u0323ng cu\u0309a ô tô khi cha\u0323y \u0111\u01b0\u01a1\u0323c qua\u0303ng \u0111\u01b0\u01a1\u0300ng 6 km la\u0300:<\/p>","options":["A.<\/strong> $1,8.10^6$<\/span> J.","B.<\/strong> $15.10^6$<\/span> J.","C.<\/strong> $1,5.10^6$<\/span> J.","D.<\/strong> $18.10^6$<\/span> J."],"correct":"4","level":"3","hint":"","answer":"Ch\u1ecdn D.<\/strong> $18.10^6$<\/span> J.<\/span><\/p>\u0110\u1ed5i \u0111\u01a1n v\u1ecb: v = 72 km\/h = 20 m\/s. $\\mathscr{P}$<\/span> = 60 kW = 60 000 W. s = 6 km = 6000 m. Ô tô ch\u1ea1y \u0111\u1ec1u, nên th\u1eddi gian ô tô ch\u1ea1y h\u1ebft qua\u0303ng \u0111\u01b0\u01a1\u0300ng 6 km la\u0300: $t=\\dfrac{s}{v}=\\dfrac{6000}{20}=300s$<\/span>. Công cu\u0309a l\u01b0\u0323c pha\u0301t \u0111ô\u0323ng cu\u0309a ô tô khi cha\u0323y \u0111\u01b0\u01a1\u0323c qua\u0303ng \u0111\u01b0\u01a1\u0300ng 6 km la\u0300: A = $\\mathscr{P}$<\/span> . t = 60 000 . 300 = $18.10^6$<\/span> J.<\/p>","type":"choose","extra_type":"classic","user_id":"131","test":"0","date":"2025-03-16 15:56:46","option_type":"math","len":0},{"id":"7961","mon_id":"1158790","chapter_id":"1159772","post_id":"8649","question":"M\u1ed9t thang máy có kh\u1ed1i l\u01b0\u1ee3ng m = 3 t\u1ea5n \u0111i lên v\u1edbi gia t\u1ed1c a = 1 m\/s². Cho g = 10 m\/s². Trong th\u1eddi gian 4s \u0111\u1ea7u tiên công su\u1ea5t trung bình c\u1ee7a thang máy là<\/p>","options":["A.<\/strong> 33kW","B.<\/strong> 8,25 kW","C.<\/strong> 5,5 kW","D.<\/strong> 45 kW"],"correct":"2","level":"3","hint":"","answer":"Ch\u1ecdn B.<\/strong> 8,25 kW.<\/span><\/p>Trong 5 s v\u1eadt \u0111i lên \u0111\u01b0\u1ee3c: $s=\\dfrac{1}{2}at^2=\\dfrac{1}{2}.1.4^2=8(m)$<\/span>.<\/p>L\u1ef1c nâng c\u1ee7a thang là F = m.a + P = m(a + g) = 3000 (1 + 10) = 33 000 N.<\/p>Công su\u1ea5t c\u1ee7a thang máy trong 4 s \u0111\u1ea7u tiên là <\/p> $\\mathscr{P}$<\/span> $=\\dfrac{A}{t}=\\dfrac{33000}{4}=8250W=8,25kW$<\/span>.<\/p>","type":"choose","extra_type":"classic","user_id":"131","test":"0","date":"2025-03-16 16:10:52","option_type":"txt","len":0},{"id":"7965","mon_id":"1158790","chapter_id":"1159772","post_id":"8649","question":"M\u1ed9t c\u1ea7n c\u1ea9u nâng v\u1eadt có kh\u1ed1i l\u01b0\u1ee3ng 500 kg b\u1eaft \u0111\u1ea7u chuy\u1ec3n \u0111\u1ed9ng nhanh d\u1ea7n \u0111\u1ec1u lên cao 18 m trong 1 phút \u1edf n\u01a1i có g = 10 m\/s². Công su\u1ea5t c\u1ee7a c\u1ea7n c\u1ea9u là bao nhiêu?<\/p>","options":["A.<\/strong> 1500,1 W.","B.<\/strong> 1501,5 W.","C.<\/strong> 1505,5 W.","D.<\/strong> 1502,1 W."],"correct":"2","level":"3","hint":"","answer":"Ch\u1ecdn B.<\/strong> 1501,5 W.<\/span><\/p>Gia t\u1ed1c c\u1ee7a c\u1ea7n c\u1ea9u khi \u0111i lên cao 18 m là<\/p> $h=\\dfrac{1}{2}at^2$<\/span> ⇒ $a=\\dfrac{2h}{t^2}=\\dfrac{2.18}{60^2}=0,01m\/s^2$<\/span>.<\/p>Theo \u0111\u1ecbnh lu\u1eadt II Newton ta có: F – P = m.a ⇒ F = m.g + m.a = m (g + a) = 500 (10 + 0,01) = 5005 N.<\/p>Công c\u1ee7a l\u1ef1c kéo A = F.s = F.h = 5005 . 18 = 90 090 J.<\/p>Công su\u1ea5t c\u1ee7a \u0111\u1ed9ng c\u01a1 là $\\mathscr{P}$<\/span> $=\\dfrac{A}{t}=\\dfrac{90090}{60}=1501,5W$<\/span>.<\/p>","type":"choose","extra_type":"classic","user_id":"131","test":"0","date":"2025-03-16 16:24:08","option_type":"txt","len":1}]}