Tác dụng làm quay của lực. Momen lực

Home Lớp 8 Khoa học tự nhiên 8 - sách Kết nối tri thức Bài 18: Tác dụng làm quay của lực. Momen lựcBài tập trung bình

{"common":{"save":0,"post_id":"8845","level":2,"total":10,"point":10,"point_extra":0},"segment":[{"id":"9169","post_id":"8845","mon_id":"1159539","chapter_id":"1159793","question":"Ho\u1ea1t \u0111\u1ed9ng nào sau \u0111ây có xu\u1ea5t hi\u1ec7n moment l\u1ef1c?<\/p>","options":["A.<\/strong> M\u1ed9t h\u1ecdc sinh ch\u01a1i trò ch\u01a1i c\u1ea7u tu\u1ed9t.","B.<\/strong> Dùng tay \u0111\u1ec3 m\u1edf ng\u0103n kéo h\u1ed9p bàn.","C.<\/strong> Dùng tay \u0111\u1ec3 \u0111\u1ea9y m\u1ed9t v\u1eadt n\u1eb7ng trên sàn.","D.<\/strong> Dùng tua vít \u0111\u1ec3 m\u1edf \u1ed1c \u0111\u01b0\u1ee3c g\u1eafn trên m\u1ea9u g\u1ed7."],"correct":"4","level":"2","hint":"Moment l\u1ef1c là tác d\u1ee5ng làm quay v\u1eadt quanh m\u1ed9t \u0111i\u1ec3m ho\u1eb7c tr\u1ee5c c\u1ed1 \u0111\u1ecbnh.<\/p>","answer":"\u0110áp án \u0111úng là: <\/strong>D.<\/strong> Dùng tua vít \u0111\u1ec3 m\u1edf \u1ed1c \u0111\u01b0\u1ee3c g\u1eafn trên m\u1ea9u g\u1ed7.<\/p>Gi\u1ea3i thích:<\/em><\/p>Khi dùng tua vít \u0111\u1ec3 m\u1edf \u1ed1c, l\u1ef1c do tay tác d\u1ee5ng lên tua vít s\u1ebd t\u1ea1o ra moment l\u1ef1c làm \u1ed1c quay quanh tr\u1ee5c c\u1ee7a nó. Các ho\u1ea1t \u0111\u1ed9ng khác không liên quan \u0111\u1ebfn chuy\u1ec3n \u0111\u1ed9ng quay quanh tr\u1ee5c.<\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"132","test":"0","date":"2025-04-15 18:36:47","option_type":"txt","len":3},{"id":"9170","post_id":"8845","mon_id":"1159539","chapter_id":"1159793","question":"\u1ede tr\u01b0\u1eddng h\u1ee3p nào sau \u0111ây, l\u1ef1c có tác d\u1ee5ng làm v\u1eadt r\u1eafn quay quanh tr\u1ee5c?<\/p>","options":["A.<\/strong> L\u1ef1c có giá n\u1eb1m trong m\u1eb7t ph\u1eb3ng vuông góc v\u1edbi tr\u1ee5c quay và c\u1eaft tr\u1ee5c quay.","B.<\/strong> L\u1ef1c có giá song song v\u1edbi tr\u1ee5c quay.","C.<\/strong> L\u1ef1c có giá c\u1eaft tr\u1ee5c quay.","D.<\/strong> L\u1ef1c có giá n\u1eb1m trong m\u1eb7t ph\u1eb3ng vuông góc v\u1edbi tr\u1ee5c quay và không c\u1eaft tr\u1ee5c quay."],"correct":"4","level":"2","hint":"Mu\u1ed1n có moment l\u1ef1c thì l\u1ef1c ph\u1ea3i t\u1ea1o ra m\u1ed9t cánh tay \u0111òn (kho\u1ea3ng cách t\u1eeb tr\u1ee5c quay \u0111\u1ebfn giá c\u1ee7a l\u1ef1c).<\/p>","answer":"\u0110áp án \u0111úng là:<\/strong> D. L\u1ef1c có giá n\u1eb1m trong m\u1eb7t ph\u1eb3ng vuông góc v\u1edbi tr\u1ee5c quay và không c\u1eaft tr\u1ee5c quay.<\/p>Gi\u1ea3i thích:<\/em> <\/p>Khi l\u1ef1c có giá n\u1eb1m trong m\u1eb7t ph\u1eb3ng vuông góc v\u1edbi tr\u1ee5c quay và không c\u1eaft tr\u1ee5c quay thì có cánh tay \u0111òn khác không → t\u1ea1o moment l\u1ef1c → v\u1eadt quay.<\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"132","test":"0","date":"2025-04-15 18:38:11","option_type":"txt","len":3},{"id":"9171","post_id":"8845","mon_id":"1159539","chapter_id":"1159793","question":"Cách d\u1ec5 nh\u1ea5t \u0111\u1ec3 m\u1edf m\u1ed9t cánh c\u1eeda b\u1eb1ng s\u1eaft n\u1eb7ng là tác d\u1ee5ng l\u1ef1c vào \u0111âu?<\/p>","options":["A.<\/strong> G\u1ea7n b\u1ea3n l\u1ec1. \n ","B.<\/strong> \u1ede gi\u1eefa c\u1eeda.","C.<\/strong> \u1ede mép c\u1eeda cách xa b\u1ea3n l\u1ec1.","D.<\/strong> \u1ede v\u1ecb trí b\u1ea5t k\u1ef3 trên c\u1eeda.<\/p> <\/p>"],"correct":"3","level":"2","hint":"Moment l\u1ef1c càng l\u1edbn khi l\u1ef1c tác d\u1ee5ng càng xa tr\u1ee5c quay (b\u1ea3n l\u1ec1).<\/p>","answer":"\u0110áp án \u0111úng là:<\/strong> C. \u1ede mép c\u1eeda cách xa b\u1ea3n l\u1ec1.<\/p>Gi\u1ea3i thích:<\/em><\/p>Khi tác d\u1ee5ng l\u1ef1c \u1edf mép c\u1eeda (xa b\u1ea3n l\u1ec1), cánh tay \u0111òn l\u1edbn → moment l\u1ef1c l\u1edbn → m\u1edf c\u1eeda d\u1ec5 dàng h\u01a1n.<\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"132","test":"0","date":"2025-04-15 18:39:19","option_type":"txt","len":2},{"id":"9172","post_id":"8845","mon_id":"1159539","chapter_id":"1159793","question":"Tác d\u1ee5ng làm quay c\u1ee7a l\u1ef1c ph\u1ee5 thu\u1ed9c vào y\u1ebfu t\u1ed1 nào?<\/p>","options":["A.<\/strong> \u0110\u1ed9 l\u1edbn c\u1ee7a l\u1ef1c.","B.<\/strong> \u0110i\u1ec3m \u0111\u1eb7t c\u1ee7a l\u1ef1c tác d\u1ee5ng.","C.<\/strong> \u0110\u1ed9 l\u1edbn c\u1ee7a l\u1ef1c và \u0111i\u1ec3m \u0111\u1eb7t c\u1ee7a l\u1ef1c.","D.<\/strong> Không ph\u1ee5 thu\u1ed9c vào b\u1ea5t k\u1ef3 y\u1ebfu t\u1ed1 nào."],"correct":"3","level":"2","hint":"Moment l\u1ef1c ph\u1ee5 thu\u1ed9c vào \u0111\u1ed9 l\u1edbn c\u1ee7a l\u1ef1c và kho\u1ea3ng cách t\u1eeb tr\u1ee5c quay \u0111\u1ebfn giá c\u1ee7a l\u1ef1c.<\/p>","answer":"\u0110áp án \u0111úng là:<\/strong> C. \u0110\u1ed9 l\u1edbn c\u1ee7a l\u1ef1c và \u0111i\u1ec3m \u0111\u1eb7t c\u1ee7a l\u1ef1c.<\/p>Gi\u1ea3i thích:<\/em><\/p>Moment l\u1ef1c \u0111\u1eb7c tr\u01b0ng cho tác d\u1ee5ng làm quay c\u1ee7a l\u1ef1c, \u0111\u01b0\u1ee3c tính theo công th\u1ee9c M=F⋅dM = F \\cdot dM=F⋅d nên ph\u1ee5 thu\u1ed9c vào \u0111\u1ed9 l\u1edbn c\u1ee7a l\u1ef1c và v\u1ecb trí tác d\u1ee5ng l\u1ef1c.<\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"132","test":"0","date":"2025-04-15 18:44:27","option_type":"txt","len":3},{"id":"9173","post_id":"8845","mon_id":"1159539","chapter_id":"1159793","question":"M\u1ed9t ng\u01b0\u1eddi mu\u1ed1n m\u1edf n\u1eafp chai b\u1eb1ng d\u1ee5ng c\u1ee5 b\u1ea9y. N\u1ebfu ng\u01b0\u1eddi này tác d\u1ee5ng cùng m\u1ed9t l\u1ef1c, cách nào sau \u0111ây s\u1ebd t\u1ea1o moment l\u1ef1c l\u1edbn nh\u1ea5t?<\/p>","options":["A.<\/strong> Tác d\u1ee5ng l\u1ef1c g\u1ea7n tr\u1ee5c xoay.","B.<\/strong> Tác d\u1ee5ng l\u1ef1c t\u1ea1i v\u1ecb trí gi\u1eefa tay \u0111òn.","C.<\/strong> Tác d\u1ee5ng l\u1ef1c \u1edf \u0111\u1ea7u xa tay \u0111òn.","D.<\/strong> Tác d\u1ee5ng l\u1ef1c không vuông góc v\u1edbi tay \u0111òn."],"correct":"3","level":"2","hint":"Moment l\u1ef1c t\u0103ng khi t\u0103ng kho\u1ea3ng cách t\u1eeb tr\u1ee5c quay \u0111\u1ebfn \u0111i\u1ec3m \u0111\u1eb7t l\u1ef1c.<\/p>","answer":"\u0110áp án \u0111úng là:<\/strong> C. Tác d\u1ee5ng l\u1ef1c \u1edf \u0111\u1ea7u xa tay \u0111òn.<\/p>Gi\u1ea3i thích:<\/em><\/p>Tác d\u1ee5ng l\u1ef1c càng xa tr\u1ee5c quay → cánh tay \u0111òn càng l\u1edbn → moment l\u1ef1c càng l\u1edbn → m\u1edf d\u1ec5 h\u01a1n.<\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"132","test":"0","date":"2025-04-15 18:52:14","option_type":"txt","len":3},{"id":"9174","post_id":"8845","mon_id":"1159539","chapter_id":"1159793","question":"Khi v\u1eb7n vòi n\u01b0\u1edbc b\u1eb1ng tay, moment l\u1ef1c s\u1ebd l\u1edbn nh\u1ea5t<\/strong> trong tr\u01b0\u1eddng h\u1ee3p nào?<\/p>","options":["A.<\/strong> Tác d\u1ee5ng l\u1ef1c vuông góc và xa tr\u1ee5c quay.","B.<\/strong> Tác d\u1ee5ng l\u1ef1c song song v\u1edbi tr\u1ee5c quay.","C.<\/strong> Tác d\u1ee5ng l\u1ef1c t\u1ea1i \u0111i\u1ec3m g\u1ea7n tr\u1ee5c quay nh\u1ea5t.","D.<\/strong> Tác d\u1ee5ng l\u1ef1c d\u1ecdc theo chi\u1ec1u tay c\u1ea7m."],"correct":"1","level":"2","hint":"L\u1ef1c có tác d\u1ee5ng quay hi\u1ec7u qu\u1ea3 nh\u1ea5t khi vuông góc v\u1edbi tay c\u1ea7m và \u1edf xa tr\u1ee5c quay.<\/p> <\/p>","answer":"\u0110áp án \u0111úng là:<\/strong> A. Tác d\u1ee5ng l\u1ef1c vuông góc và xa tr\u1ee5c quay.<\/p>Gi\u1ea3i thích:<\/em><\/p>Moment l\u1ef1c l\u1edbn nh\u1ea5t khi l\u1ef1c tác d\u1ee5ng vuông góc v\u1edbi tay \u0111òn và tay \u0111òn dài nh\u1ea5t.<\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"132","test":"0","date":"2025-04-15 18:54:43","option_type":"txt","len":3},{"id":"9175","post_id":"8845","mon_id":"1159539","chapter_id":"1159793","question":"Khi dùng cùng m\u1ed9t l\u1ef1c nh\u01b0ng moment l\u1ef1c v\u1eabn nh\u1ecf, nguyên nhân có th\u1ec3 là:<\/p>","options":["A.<\/strong> Cánh tay \u0111òn quá ng\u1eafn.","B.<\/strong> Dùng sai lo\u1ea1i l\u1ef1c.","C.<\/strong> V\u1eadt có kh\u1ed1i l\u01b0\u1ee3ng nh\u1ecf.","D.<\/strong> V\u1eadt n\u1eb1m cân b\u1eb1ng."],"correct":"1","level":"2","hint":"Moment l\u1ef1c ph\u1ee5 thu\u1ed9c vào \u0111\u1ed9 dài t\u1eeb tr\u1ee5c quay \u0111\u1ebfn giá c\u1ee7a l\u1ef1c.<\/p>","answer":"\u0110áp án \u0111úng là:<\/strong> A. Cánh tay \u0111òn quá ng\u1eafn.<\/p>Gi\u1ea3i thích:<\/em><\/p>Khi cánh tay \u0111òn ng\u1eafn → $d$<\/span> nh\u1ecf → moment l\u1ef1c $M=F.d$<\/span> nh\u1ecf → tác d\u1ee5ng quay y\u1ebfu.<\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"132","test":"0","date":"2025-04-15 18:56:35","option_type":"txt","len":2},{"id":"9388","post_id":"8845","mon_id":"1159539","chapter_id":"1159793","question":"M\u1ed9t ng\u01b0\u1eddi dùng c\u1edd lê dài 25 cm \u0111\u1ec3 m\u1edf \u1ed1c. \u0110\u1ec3 t\u0103ng moment l\u1ef1c mà không thay \u0111\u1ed5i \u0111\u1ed9 l\u1edbn l\u1ef1c, ng\u01b0\u1eddi \u0111ó nên:<\/p>","options":["A.<\/strong> C\u1ea7m c\u1edd lê g\u1ea7n tr\u1ee5c xoay h\u01a1n.","B.<\/strong> C\u1ea7m c\u1edd lê \u1edf gi\u1eefa.","C.<\/strong> C\u1ea7m c\u1edd lê \u1edf \u0111\u1ea7u xa nh\u1ea5t và gi\u1eef h\u01b0\u1edbng l\u1ef1c vuông góc.","D.<\/strong> Dùng l\u1ef1c theo chi\u1ec1u d\u1ecdc tr\u1ee5c xoay."],"correct":"3","level":"2","hint":"Moment l\u1ef1c ph\u1ee5 thu\u1ed9c vào cánh tay \u0111òn và h\u01b0\u1edbng l\u1ef1c.<\/p>","answer":"\u0110áp án \u0111úng là:<\/strong> C. C\u1ea7m c\u1edd lê \u1edf \u0111\u1ea7u xa nh\u1ea5t và gi\u1eef h\u01b0\u1edbng l\u1ef1c vuông góc.<\/p>Gi\u1ea3i thích:<\/em><\/p>Khi l\u1ef1c \u0111\u01b0\u1ee3c tác d\u1ee5ng \u1edf \u0111\u1ea7u xa và vuông góc, cánh tay \u0111òn dài nh\u1ea5t → moment l\u1ef1c l\u1edbn nh\u1ea5t.<\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"132","test":"0","date":"2025-04-18 07:56:30","option_type":"txt","len":3},{"id":"9389","post_id":"8845","mon_id":"1159539","chapter_id":"1159793","question":"T\u1ea1i sao ng\u01b0\u1eddi ta th\u01b0\u1eddng thi\u1ebft k\u1ebf tay n\u1eafm c\u1eeda \u1edf phía \u0111\u1ed1i di\u1ec7n b\u1ea3n l\u1ec1?<\/p>","options":["A.<\/strong> \u0110\u1ec3 d\u1ec5 gi\u1eef th\u0103ng b\u1eb1ng.","B.<\/strong> \u0110\u1ec3 t\u0103ng \u0111\u1ed9 th\u1ea9m m\u1ef9.","C.<\/strong> \u0110\u1ec3 gi\u1ea3m ma sát.","D.<\/strong> \u0110\u1ec3 t\u1ea1o moment l\u1ef1c l\u1edbn h\u01a1n khi m\u1edf c\u1eeda."],"correct":"4","level":"2","hint":"M\u1edf c\u1eeda d\u1ec5 h\u01a1n n\u1ebfu moment l\u1ef1c l\u1edbn.<\/p>","answer":"\u0110áp án \u0111úng là:<\/strong> D. \u0110\u1ec3 t\u1ea1o moment l\u1ef1c l\u1edbn h\u01a1n khi m\u1edf c\u1eeda.<\/p>Gi\u1ea3i thích:<\/em><\/p>Tay n\u1eafm càng xa b\u1ea3n l\u1ec1 → cánh tay \u0111òn càng dài → d\u1ec5 m\u1edf c\u1eeda nh\u1edd moment l\u1ef1c l\u1edbn h\u01a1n.<\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"132","test":"0","date":"2025-04-18 07:57:44","option_type":"txt","len":2},{"id":"9390","post_id":"8845","mon_id":"1159539","chapter_id":"1159793","question":"M\u1ed9t ng\u01b0\u1eddi dùng búa \u0111\u1ec3 b\u1ea9y \u0111inh ra kh\u1ecfi g\u1ed7. Khi ng\u01b0\u1eddi \u0111ó tác d\u1ee5ng l\u1ef1c \u1edf \u0111âu thì hi\u1ec7u qu\u1ea3 nh\u1ea5t?<\/p>","options":["A.<\/strong> G\u1ea7n \u0111i\u1ec3m t\u1ef1a c\u1ee7a búa.","B.<\/strong> \u1ede gi\u1eefa cán búa.","C.<\/strong> \u1ede \u0111\u1ea7u cán búa.","D.<\/strong> B\u1ea5t k\u1ef3 v\u1ecb trí nào."],"correct":"3","level":"2","hint":"Cánh tay \u0111òn càng dài → moment l\u1ef1c càng l\u1edbn.<\/p>","answer":"\u0110áp án \u0111úng là:<\/strong> C. \u1ede \u0111\u1ea7u cán búa.<\/p>Gi\u1ea3i thích:<\/em><\/p>Tác d\u1ee5ng l\u1ef1c \u1edf \u0111\u1ea7u cán giúp t\u1ea1o moment l\u1ef1c l\u1edbn, d\u1ec5 nh\u1ed5 \u0111inh h\u01a1n.<\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"132","test":"0","date":"2025-04-18 07:59:29","option_type":"txt","len":2}]}