{"segment":[{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[4]],"list":[{"point":5,"ques":"V\u1eadn t\u1ed1c cho bi\u1ebft g\u00ec:<br\/>I.T\u00ednh nhanh hay ch\u1eadm c\u1ee7a chuy\u1ec3n \u0111\u1ed9ng.<br\/>II.Qu\u00e3ng \u0111\u01b0\u1eddng \u0111i \u0111\u01b0\u1ee3c.<br\/>III.Qu\u00e3ng \u0111\u01b0\u1eddng \u0111i \u0111\u01b0\u1ee3c trong m\u1ed9t \u0111\u01a1n v\u1ecb th\u1eddi gian.<br\/>IV.T\u00e1c d\u1ee5ng c\u1ee7a v\u1eadt n\u00e0y l\u00ean v\u1eadt kh\u00e1c.<br\/>Ch\u1ecdn \u0111\u00e1p \u00e1n ch\u1ee9a c\u00e1c c\u00e2u tr\u1ea3 l\u1eddi \u0111\u00fang? ","select":["A. I;II v\u00e0 III. ","B. II; III v\u00e0 IV.","C. C\u1ea3 I; II; III v\u00e0 IV. ","D. I v\u00e0 III."],"hint":"","explain":"<span class='basic_left'>\u0110\u1ed9 l\u1edbn c\u1ee7a v\u1eadn t\u1ed1c cho bi\u1ebft m\u1ee9c \u0111\u1ed9 nhanh hay ch\u1eadm c\u1ee7a chuy\u1ec3n \u0111\u1ed9ng.<br\/>\u0110\u01b0\u1ee3c x\u00e1c \u0111\u1ecbnh b\u1eb1ng \u0111\u1ed9 d\u00e0i qu\u00e3ng \u0111\u01b0\u1eddng \u0111i \u0111\u01b0\u1ee3c trong m\u1ed9t \u0111\u01a1n v\u1ecb th\u1eddi gian.<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 D.<\/span><\/span> ","column":2}]}],"id_ques":2500},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":"Tr\u00e1i \u0110\u1ea5t quay quanh M\u1eb7t Tr\u1eddi m\u1ed9t v\u00f2ng trong th\u1eddi gian m\u1ed9t n\u0103m (trung b\u00ecnh l\u00e0 $365$ ng\u00e0y). Bi\u1ebft v\u1eadn t\u1ed1c quay c\u1ee7a Tr\u00e1i \u0110\u1ea5t b\u1eb1ng $108 000km\/h$. L\u1ea5y $\\pi \u2248 3,14$ th\u00ec gi\u00e1 tr\u1ecb trung b\u00ecnh b\u00e1n k\u00ednh qu\u1ef9 \u0111\u1ea1o c\u1ee7a Tr\u00e1i \u0110\u1ea5t quanh M\u1eb7t Tr\u1eddi l\u00e0:","select":["A. 145.000.000km.","B. 150.000.000km.","C. 150.649.682km.","D. 149.300.000km."],"hint":"","explain":"<span class='basic_left'>Chi\u1ec1u d\u00e0i m\u00e0 Tr\u00e1i \u0110\u1ea5t quay trong 1 n\u0103m:<br\/> $S = v.t = 365 \\times 24 x 108.000 = 946.080.000 km$.<br\/> B\u00e1n k\u00ednh Tr\u00e1i \u0110\u1ea5t:<br\/> $R=\\dfrac{S}{2\\pi } = 150.649.682 km$. <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 C.<\/span><\/span> ","column":2}]}],"id_ques":2501},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":"M\u1ed9t ng\u01b0\u1eddi \u0111\u1ee9ng g\u1ea7n v\u00e1ch n\u00fai \u0111\u00e1 v\u00e0 g\u1ecdi to h\u01b0\u1edbng v\u1ec1 ph\u00eda n\u00fai th\u00ec th\u1ea5y kho\u1ea3ng th\u1eddi gian t\u1eeb l\u00fac g\u1ecdi t\u1edbi l\u00fac nghe \u0111\u01b0\u1ee3c ti\u1ebfng v\u1ecdng l\u1ea1i l\u00e0 2 gi\u00e2y. Bi\u1ebft v\u1eadn t\u1ed1c truy\u1ec1n \u00e2m thanh trong kh\u00f4ng kh\u00ed l\u00e0 $340m\/s$, h\u1ecfi kho\u1ea3ng c\u00e1ch t\u1eeb ng\u01b0\u1eddi \u0111\u00f3 \u0111\u1ebfn v\u00e1ch n\u00fai l\u00e0 bao nhi\u00eau? ","select":["A. 680m","B. 340m","C. 170m","D. 85m"],"hint":"","explain":"<span class='basic_left'>Kho\u1ea3ng c\u00e1ch t\u1eeb ng\u01b0\u1eddi \u0111\u00f3 \u0111\u1ebfn v\u00e1ch n\u00fai l\u00e0:<br\/> $S=\\dfrac{v\\times t}{2}=\\dfrac{340\\times 2}{2}=340m$ <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span> ","column":2}]}],"id_ques":2502},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":"B\u00e1nh xe c\u1ee7a m\u1ed9t \u00f4 t\u00f4 du l\u1ecbch c\u00f3 b\u00e1n k\u00ednh $25cm$. N\u1ebfu xe ch\u1ea1y v\u1edbi v\u1eadn t\u1ed1c $54km\/h$ v\u00e0 l\u1ea5y $\\pi \u2248 3,14 $ th\u00ec s\u1ed1 v\u00f2ng quay b\u00e1nh xe c\u1ee7a m\u1ed7i m\u1ed9t gi\u1edd l\u00e0:","select":["A. 34 v\u00f2ng","B. 17197 v\u00f2ng ","C. 34395 v\u00f2ng","D. 17190 v\u00f2ng "],"hint":"","explain":"<span class='basic_left'>Ta c\u00f3: $r = 25cm \\Rightarrow d = 50cm = 0,5m$ <br\/>Qu\u00e3ng \u0111\u01b0\u1eddng m\u00e0 b\u00e1nh xe \u0111i \u0111\u01b0\u1ee3c trong 1 gi\u1edd:<br\/> $s = v.t = 54.1 = 54 km = 54 000m$<br\/>Chu vi m\u1ed9t v\u00f2ng quay: $3,14 \\times 0,5 = 1,57m$<br\/>S\u1ed1 v\u00f2ng quay c\u1ee7a b\u00e1nh xe trong m\u1ed9t gi\u1edd l\u00e0: $\\dfrac{54000}{1,57}\u224834395$ v\u00f2ng.<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 C.<\/span><\/span> ","column":2}]}],"id_ques":2503},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":"Trong \u0111\u00eam t\u1ed1i t\u1eeb l\u00fac th\u1ea5y tia ch\u1edbp s\u00e1ng ch\u00f3i \u0111\u1ebfn khi nghe th\u1ea5y ti\u1ebfng bom n\u1ed5 kho\u1ea3ng $15$ gi\u00e2y. H\u1ecfi ch\u1ed7 bom n\u1ed5 c\u00e1ch ng\u01b0\u1eddi quan s\u00e1t bao xa? Bi\u1ebft v\u1eadn t\u1ed1c truy\u1ec1n \u00e2m trong kh\u00f4ng kh\u00ed b\u1eb1ng $340 m\/s$.","select":["A. 5100 m","B. 5000 m","C. 5200 m","D. 5300 m"],"hint":"","explain":"<span class='basic_left'>Bom n\u1ed5 c\u00e1ch ng\u01b0\u1eddi quan s\u00e1t:<br\/> $S = v.t = 340. 15 = 5100m$<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 A.<\/span><\/span> ","column":2}]}],"id_ques":2504},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":"Chuy\u1ec3n \u0111\u1ed9ng c\u1ee7a ph\u00e2n t\u1eed hi\u0111r\u00f4 \u1edf ${0}^\\circ C$ c\u00f3 v\u1eadn t\u1ed1c $1692m\/s$, c\u1ee7a v\u1ec7 tinh nh\u00e2n t\u1ea1o c\u1ee7a Tr\u00e1i \u0110\u1ea5t c\u00f3 v\u1eadn t\u1ed1c $28800km\/h$. H\u1ecfi chuy\u1ec3n \u0111\u1ed9ng n\u00e0o nhanh h\u01a1n ?","select":["A. Chuy\u1ec3n \u0111\u1ed9ng c\u1ee7a ph\u00e2n t\u1eed hi\u0111r\u00f4 nhanh h\u01a1n. ","B. Chuy\u1ec3n \u0111\u1ed9ng c\u1ee7a v\u1ec7 tinh nh\u00e2n t\u1ea1o c\u1ee7a Tr\u00e1i \u0110\u1ea5t nhanh h\u01a1n. ","C. Hai chuy\u1ec3n \u0111\u1ed9ng b\u1eb1ng nhau. ","D. T\u1ea5t c\u1ea3 \u0111\u1ec1u sai."],"hint":"","explain":"<span class='basic_left'>\u0110\u1ed5i v\u1ec1 c\u00f9ng \u0111\u01a1n v\u1ecb r\u1ed3i so s\u00e1nh.<br\/> V\u1eadn t\u1ed1c c\u1ee7a Hi\u0111r\u00f4 $= 1692 m\/s$.<br\/>V\u1eadn t\u1ed1c c\u1ee7a v\u1ec7 tinh nh\u00e2n t\u1ea1o: $\\dfrac{28800}{3,6}=8000$ m\/s.<br\/>Chuy\u1ec3n \u0111\u1ed9ng c\u1ee7a c\u1ee7a v\u1ec7 tinh nh\u00e2n t\u1ea1o c\u1ee7a Tr\u00e1i \u0110\u1ea5t nhanh h\u01a1n. <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><br\/> <span class='basic_green'>Ghi nh\u1edb: <\/span> Mu\u1ed1n \u0111\u1ed5i t\u1eeb \u0111\u01a1n v\u1ecb km\/h sang \u0111\u01a1n v\u1ecb m\/s ta chia cho $3,6$<br\/>V\u00ec d\u1ee5: $18 km\/h = 5 m\/s$<\/span> ","column":1}]}],"id_ques":2505},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":"M\u1ed9t m\u00e1y bay bay v\u1edbi v\u1eadn t\u1ed1c 800km\/h t\u1eeb H\u00e0 N\u1ed9i \u0111\u1ebfn Th\u00e0nh ph\u1ed1 H\u1ed3 Ch\u00ed Minh. N\u1ebfu \u0111\u01b0\u1eddng bay H\u00e0 N\u1ed9i-Th\u00e0nh ph\u1ed1 H\u1ed3 Ch\u00ed Minh d\u00e0i 1400km, th\u00ec m\u00e1y bay ph\u1ea3i bay trong bao nhi\u00eau l\u00e2u?","select":["A. 1gi\u1edd 20ph\u00fat. ","B. 1gi\u1edd 30ph\u00fat","C. 1gi\u1edd 45ph\u00fat. ","D. 2 gi\u1edd. "],"hint":"","explain":"<span class='basic_left'>Ta c\u00f3: $v = 800 km\/h, S = 1400 km. N\u00ean v = St \u21d2$ $t=\\dfrac{S}{v}=\\dfrac{1400}{800}=1,75h = 1$ gi\u1edd $45$ ph\u00fat. <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 C.<\/span><\/span> ","column":2}]}],"id_ques":2506},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":"Hai ng\u01b0\u1eddi \u0111\u1ea1p xe. Ng\u01b0\u1eddi th\u1ee9 nh\u1ea5t \u0111i qu\u00e3ng \u0111\u01b0\u1eddng $300m$ h\u1ebft $1$ ph\u00fat. Ng\u01b0\u1eddi th\u1ee9 hai \u0111i qu\u00e3ng \u0111\u01b0\u1eddng $7,5km$ h\u1ebft $0,5$ gi\u1edd. Ng\u01b0\u1eddi n\u00e0o \u0111i nhanh h\u01a1n ?","select":["A. Ng\u01b0\u1eddi th\u1ee9 nh\u1ea5t nhanh h\u01a1n. ","B. Ng\u01b0\u1eddi th\u1ee9 hai nhanh h\u01a1n. ","C. Hai ng\u01b0\u1eddi \u0111i b\u1eb1ng nhau. ","D. T\u1ea5t c\u1ea3 \u0111\u1ec1u sai."],"hint":"","explain":"<span class='basic_left'>V\u1eadn t\u1ed1c ng\u01b0\u1eddi th\u1ee9 1:<br\/>${{v}_{1}}=\\dfrac{{{S}_{1}}}{{{t}_{1}}}=\\dfrac{300}{60}=5$<br\/>V\u1eadn t\u1ed1c ng\u01b0\u1eddi th\u1ee9 2:<br\/>${{v}_{2}}=\\dfrac{{{S}_{2}}}{{{t}_{2}}}=\\dfrac{7500}{1800}=4,17$ <br\/>Ng\u01b0\u1eddi th\u1ee9 nh\u1ea5t nhanh h\u01a1n: ${{v}_{1}}>{{v}_{2}}$ <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 A.<\/span><\/span> ","column":2}]}],"id_ques":2507},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":"Hai ng\u01b0\u1eddi \u0111\u1ea1p xe. Ng\u01b0\u1eddi th\u1ee9 nh\u1ea5t \u0111i qu\u00e3ng \u0111\u01b0\u1eddng $300m$ h\u1ebft $1$ ph\u00fat. <br\/>Ng\u01b0\u1eddi th\u1ee9 hai \u0111i qu\u00e3ng \u0111\u01b0\u1eddng $7,5km$ h\u1ebft $0,5h$.<br\/> N\u1ebfu hai ng\u01b0\u1eddi c\u00f9ng kh\u1edfi h\u00e0nh m\u1ed9t l\u00fac v\u00e0 \u0111i c\u00f9ng chi\u1ec1u th\u00ec sau $20$ ph\u00fat, hai ng\u01b0\u1eddi c\u00e1ch nhau bao nhi\u00eau $km$?","select":["A. 1km","B. 2km","C. 3km","D. 4km"],"hint":"","explain":"<span class='basic_left'>${{S}_{1}}={{v}_{1}}\\times t=5\\times 1200=6000m$ <br\/>${{S}_{2}}={{v}_{2}}\\times t=4,17\\times 1200=5004m$ <br\/>$S={{S}_{1}}-{{S}_{2}}=6000-5004=996m\\approx 1km$ <br\/>V\u1eady sau $20$ ph\u00fat $2$ ng\u01b0\u1eddi c\u00e1ch nhau kho\u1ea3ng $1km$.<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 A.<\/span><\/span> ","column":2}]}],"id_ques":2508},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":"M\u1ed9t \u00f4 t\u00f4 kh\u1edfi h\u00e0nh t\u1eeb H\u00e0 N\u1ed9i l\u00fac $8$ gi\u1edd, \u0111\u1ebfn H\u1ea3i Ph\u00f2ng l\u00fac $10$ gi\u1edd. Cho bi\u1ebft \u0111\u01b0\u1eddng H\u00e0 N\u1ed9i \u2013 H\u1ea3i Ph\u00f2ng d\u00e0i $100km$. T\u00ednh v\u1eadn t\u1ed1c c\u1ee7a \u00f4 t\u00f4?","select":["A. $30km\/h$. ","B. $40km\/h$. ","C. $50km\/h$. ","D. $60km\/h$."],"hint":"","explain":"<span class='basic_left'>$S = 100 km, t = 10h \u2013 8h = 2h$ <br\/>V\u1eadn t\u1ed1c c\u1ee7a \u00f4t\u00f4: $v=\\dfrac{S}{t}=\\dfrac{100}{2}=50km\/h$ <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 C.<\/span><\/span> ","column":2}]}],"id_ques":2509},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":"\u0110\u01a1n v\u1ecb v\u1eadn t\u1ed1c l\u00e0: ","select":["A. $km.h$","B. $m.s$","C. $km\/h$","D. $s\/m$"],"hint":"","explain":"<span class='basic_left'>\u0110\u01a1n v\u1ecb v\u1eadn t\u1ed1c l\u00e0 $km\/h$.<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 C.<\/span><\/span> ","column":2}]}],"id_ques":2510},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":"L\u00fac 6h s\u00e1ng, C\u01b0\u1eddng ch\u1ea1y th\u1ec3 d\u1ee5c t\u1eeb nh\u00e0 ra c\u00f4ng vi\u00ean. Bi\u1ebft t\u1eeb nh\u00e0 ra c\u00f4ng vi\u00ean d\u00e0i $5 km$. C\u01b0\u1eddng ch\u1ea1y v\u1edbi v\u1eadn t\u1ed1c $5km\/h$. H\u1ecfi th\u1eddi gian \u0111\u1ec3 C\u01b0\u1eddng ch\u1ea1y v\u1ec1 t\u1edbi nh\u00e0 l\u00e0 bao nhi\u00eau?","select":["A. 5 gi\u1edd 30 ph\u00fat","B. 6 gi\u1edd","C. 8 gi\u1edd","D. 0,5 gi\u1edd"],"hint":"","explain":"<span class='basic_left'>Th\u1eddi gian ch\u1ea1y c\u1ea3 \u0111i l\u1eabn v\u1ec1 l\u00e0: $\\dfrac{5\\times 2}{5} = 2h$ <br\/>V\u1eady C\u01b0\u1eddng v\u1ec1 t\u1edbi nh\u00e0 l\u00fac $8$ gi\u1edd. <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 C.<\/span><\/span> ","column":2}]}],"id_ques":2511},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":"Kho\u1ea3ng c\u00e1ch t\u1eeb sao Kim \u0111\u1ebfn M\u1eb7t Tr\u1eddi b\u1eb1ng 0,72 \u0111\u01a1n v\u1ecb thi\u00ean v\u0103n (\u0111vtv). Bi\u1ebft 1 \u0111vtv = 150 000 000 km, v\u1eadn t\u1ed1c \u00e1nh s\u00e1ng b\u1eb1ng 300 000 km\/s. T\u00ednh th\u1eddi gian \u00e1nh s\u00e1ng truy\u1ec1n t\u1eeb M\u1eb7t Tr\u1eddi t\u1edbi sao Kim? ","select":["A. 5 ph\u00fat","B. 6 ph\u00fat","C. 7 ph\u00fat","D. 8 ph\u00fat"],"hint":"","explain":"<span class='basic_left'>Ta c\u00f3: $S = 0,72 \\times 150000000 = 108000000 km. $ <br\/> $v = 300 000 km\/s$ <br\/>Th\u1eddi gian \u00e1nh s\u00e1ng truy\u1ec1n t\u1eeb m\u1eb7t tr\u1eddi \u0111\u1ebfn sao Kim:<br\/>$t=\\dfrac{S}{v}=\\dfrac{108000000}{30000}=360s=6$ ph\u00fat. <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span> ","column":2}]}],"id_ques":2512},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":"<span class='basic_left'>H\u00e3y s\u1eafp x\u1ebfp c\u00e1c v\u1eadn t\u1ed1c sau theo th\u1ee9 t\u1ef1 t\u1eeb nh\u1ecf \u0111\u1ebfn l\u1edbn. <br\/> \u2013 V\u1eadn t\u1ed1c t\u00e0u h\u1ecfa: 54km\/h <br\/> \u2013 V\u1eadn t\u1ed1c chim \u0111\u1ea1i b\u00e0ng: 24m\/s <br\/> \u2013 V\u1eadn t\u1ed1c b\u01a1i c\u1ee7a m\u1ed9t con c\u00e1: 6000 cm\/ph\u00fat <br\/> \u2013 V\u1eadn t\u1ed1c quay c\u1ee7a Tr\u00e1i \u0110\u1ea5t quanh M\u1eb7t Tr\u1eddi: 108 000km\/h.<\/span> ","select":["A. V\u1eadn t\u1ed1c quay c\u1ee7a Tr\u00e1i \u0110\u1ea5t quanh M\u1eb7t Tr\u1eddi < v\u1eadn t\u1ed1c c\u1ee7a t\u00e0u h\u1ecfa < v\u1eadn t\u1ed1c chim \u0111\u1ea1i b\u00e0ng < v\u1eadn t\u1ed1c b\u01a1i c\u1ee7a con c\u00e1. ","B. V\u1eadn t\u1ed1c b\u01a1i c\u1ee7a con c\u00e1 < v\u1eadn t\u1ed1c chim \u0111\u1ea1i b\u00e0ng < v\u1eadn t\u1ed1c c\u1ee7a t\u00e0u h\u1ecfa < v\u1eadn t\u1ed1c quay c\u1ee7a Tr\u00e1i \u0110\u1ea5t quanh M\u1eb7t Tr\u1eddi. ","C. V\u1eadn t\u1ed1c b\u01a1i c\u1ee7a con c\u00e1 < v\u1eadn t\u1ed1c c\u1ee7a t\u00e0u h\u1ecfa < v\u1eadn t\u1ed1c chim \u0111\u1ea1i b\u00e0ng < v\u1eadn t\u1ed1c quay c\u1ee7a Tr\u00e1i \u0110\u1ea5t quanh M\u1eb7t Tr\u1eddi. ","D. V\u1eadn t\u1ed1c b\u01a1i c\u1ee7a con c\u00e1 < v\u1eadn t\u1ed1c quay c\u1ee7a Tr\u00e1i \u0110\u1ea5t quanh M\u1eb7t Tr\u1eddi < v\u1eadn t\u1ed1c c\u1ee7a t\u00e0u h\u1ecfa < v\u1eadn t\u1ed1c chim \u0111\u1ea1i b\u00e0ng. "],"hint":"","explain":"<span class='basic_left'>V\u1eadn t\u1ed1c t\u00e0u h\u1ecfa ${{v}_{1}} = 15m\/s$<br\/>V\u1eadn t\u1ed1c chim \u0111\u1ea1i b\u00e0ng: ${{v}_{2}} = 24m\/s$<br\/>V\u1eadn t\u1ed1c b\u01a1i c\u1ee7a m\u1ed9t con c\u00e1: ${{v}_{3}} = 1m\/s$<br\/>V\u1eadn t\u1ed1c quay c\u1ee7a Tr\u00e1i \u0110\u1ea5t quanh M\u1eb7t Tr\u1eddi: ${{v}_{4}}= 30 000m\/s$<br\/>Mu\u1ed1n so s\u00e1nh c\u00e1c v\u1eadn t\u1ed1c kh\u00e1c nhau c\u1ea7n \u0111\u1ed5i ch\u00fang ra c\u00f9ng 1 \u0111\u01a1n v\u1ecb.<br\/>K\u1ebft qu\u1ea3: V\u1eadn t\u1ed1c b\u01a1i c\u1ee7a con c\u00e1 < v\u1eadn t\u1ed1c c\u1ee7a t\u00e0u h\u1ecfa < v\u1eadn t\u1ed1c chim \u0111\u1ea1i b\u00e0ng < v\u1eadn t\u1ed1c quay c\u1ee7a Tr\u00e1i \u0110\u1ea5t quanh M\u1eb7t Tr\u1eddi.<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 C.<\/span><\/span> ","column":1}]}],"id_ques":2513},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/vatly/bai2/lv2/img\/h0.jpg'\/><\/center>\u0110\u1ed3 th\u1ecb n\u00e0o sau \u0111\u00e2y di\u1ec5n t\u1ea3 s\u1ef1 ph\u1ee5 thu\u1ed9c c\u1ee7a \u0111\u01b0\u1eddng \u0111i theo v\u1eadn t\u1ed1c v\u00e0 th\u1eddi gian:","select":["A. H\u00ecnh A","B. H\u00ecnh B","C. H\u00ecnh C","D. H\u00ecnh D"],"hint":"","explain":"<span class='basic_left'>S\u1ef1 ph\u1ee5 thu\u1ed9c c\u1ee7a \u0111\u01b0\u1eddng \u0111i theo v\u1eadn t\u1ed1c v\u00e0 th\u1eddi gian l\u00e0 tuy\u1ebfn t\u00ednh v\u00e0 \u0111i qua g\u1ed1c t\u1ecda \u0111\u1ed9. N\u00ean h\u00ecnh A bi\u1ec3u di\u1ec5n \u0111\u00fang.<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 A.<\/span><\/span> ","column":2}]}],"id_ques":2514},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":"H\u00f2a v\u00e0 V\u1ebd c\u00f9ng \u0111\u1ea1p xe t\u1eeb c\u1ea7u Ph\u00fa B\u00e0i l\u00ean tr\u01b0\u1eddng \u0110HSP d\u00e0i 18km. H\u00f2a \u0111\u1ea1p li\u00ean t\u1ee5c kh\u00f4ng ngh\u1ec9 v\u1edbi v\u1eadn t\u1ed1c 18km\/h. V\u1ebd \u0111i s\u1edbm h\u01a1n H\u00f2a 15 ph\u00fat nh\u01b0ng d\u1ecdc \u0111\u01b0\u1eddng ngh\u1ec9 ch\u00e2n u\u1ed1ng cafe m\u1ea5t 30 ph\u00fat. H\u1ecfi V\u1ebd ph\u1ea3i \u0111\u1ea1p xe v\u1edbi v\u1eadn t\u1ed1c bao nhi\u00eau \u0111\u1ec3 t\u1edbi tr\u01b0\u1eddng c\u00f9ng l\u00fac v\u1edbi H\u00f2a?","select":["A. 16km\/h","B. 18km\/h","C. 24km\/h","D. 20km\/h"],"hint":"","explain":"<span class='basic_left'>Th\u1eddi gian H\u00f2a \u0111i t\u1eeb Ph\u00fa B\u00e0i l\u00ean \u0110HSP l\u00e0:<br\/> ${{t}_{1}}=\\dfrac{s}{{{v}_{1}}}=\\dfrac{18}{18}=1h$<br\/>V\u1ebd \u0111i s\u1edbm h\u01a1n $15$ ph\u00fat v\u00e0 ngh\u1ec9 ch\u00e2n $30$ ph\u00fat n\u00ean th\u1eddi gian V\u1ebd ph\u1ea3i \u0111i \u0111\u1ec3 t\u1edbi c\u00f9ng l\u00fac l\u00e0: <br\/>${{t}_{2}}={{t}_{1}}-\\dfrac{1}{2}+\\dfrac{1}{4}=1-\\dfrac{1}{2}+\\dfrac{1}{4}=\\dfrac{3}{4}h$ <br\/>V\u1ebd ph\u1ea3i \u0111\u1ea1p xe v\u1edbi v\u1eadn t\u1ed1c:<br\/>${{v}_{2}}=\\dfrac{s}{{{t}_{2}}}=\\dfrac{18}{\\left( \\dfrac{3}{4} \\right)}=24km\/h$ <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 C.<\/span><\/span> ","column":2}]}],"id_ques":2515},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[4]],"list":[{"point":5,"ques":"Hai \u00f4 t\u00f4 chuy\u1ec3n \u0111\u1ed9ng th\u1eb3ng \u0111\u1ec1u kh\u1edfi h\u00e0nh \u0111\u1ed3ng th\u1eddi \u1edf 2 \u0111\u1ecba \u0111i\u1ec3m c\u00e1ch nhau 20km. N\u1ebfu \u0111i ng\u01b0\u1ee3c chi\u1ec1u thi sau 15 ph\u00fat ch\u00fang g\u1eb7p nhau. N\u1ebfu \u0111i c\u00f9ng chi\u1ec1u sau 30 ph\u00fat th\u00ec ch\u00fang \u0111u\u1ed5i k\u1ecbp nhau. V\u1eadn t\u1ed1c c\u1ee7a hai xe \u0111\u00f3 l\u00e0? ","select":["A. 20km\/h v\u00e0 30km\/h.","B. 30km\/h v\u00e0 40km\/h.","C. 40km\/h v\u00e0 20km\/h.","D. 20km\/h v\u00e0 60km\/h."],"hint":"","explain":"<span class='basic_left'>Ta g\u1ecdi qu\u00e3ng \u0111\u01b0\u1eddng, v\u1eadn t\u1ed1c v\u00e0 th\u1eddi gian \u0111i \u0111\u01b0\u1ee3c l\u1ea7n l\u01b0\u1ee3t l\u00e0 ${{s}_{1}}$,${{v}_{1}}$,${{t}_{1}}$ v\u00e0 ${{s}_{2}}$,${{v}_{2}}$,${{t}_{2}}$.<br\/>Ta c\u00f3, khi \u0111i c\u00f9ng chi\u1ec1u th\u00ec: ${{s}_{1}} - {{s}_{2}} = 20km$ v\u1edbi $t = 0,5 h$ <br\/>V\u00ec 2 xe xu\u1ea5t ph\u00e1t c\u00f9ng l\u00fac v\u00e0 g\u1eb7p nhau n\u00ean th\u1eddi gian 2 xe \u0111i nh\u01b0 nhau ngh\u0129a l\u00e0 ${{t}_{1}} = {{t}_{2}}$. <br\/>Khi \u0111i ng\u01b0\u1ee3c chi\u1ec1u: ${{s}_{1}} + {{s}_{2}} = 20km $ v\u1edbi $t = \\dfrac{1}{4}h$ <br\/>V\u1eady ta c\u00f3 h\u1ec7 ph\u01b0\u01a1ng tr\u00ecnh v\u1eadn t\u1ed1c: <br\/>${{v}_{1}} + {{v}_{2}} = \\dfrac{20}{0,25} = 80$ <br\/>${{v}_{1}} - {{v}_{2}} = \\dfrac{20}{0,5}= 40$ <br\/>Gi\u1ea3i ra \u0111\u01b0\u1ee3c: ${{v}_{1}} = 60km\/h ,{{v}_{2}}= 20km\/h$. <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 D.<\/span><\/span> ","column":2}]}],"id_ques":2516},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":"L\u00fac 5 gi\u1edd s\u00e1ng T\u00e2n ch\u1ea1y th\u1ec3 d\u1ee5c t\u1eeb nh\u00e0 ra c\u1ea7u \u0110\u1ea1i Giang. Bi\u1ebft t\u1eeb nh\u00e0 ra c\u1ea7u \u0110\u1ea1i Giang d\u00e0i 2,5 km. T\u00e2n ch\u1ea1y v\u1edbi v\u1eadn t\u1ed1c 5km\/h. H\u1ecfi T\u00e2n v\u1ec1 t\u1edbi nh\u00e0 l\u00fac m\u1ea5y gi\u1edd?","select":["A. 5 gi\u1edd 30 ph\u00fat","B. 6 gi\u1edd","C. 1 gi\u1edd","D. 0,5 gi\u1edd"],"hint":"","explain":"<span class='basic_left'>Th\u1eddi gian ch\u1ea1y c\u1ea3 \u0111i l\u1eabn v\u1ec1 l\u00e0: $\\dfrac{2,5\\times 2}{5} = 1h$ <br\/>V\u1eady T\u00e2n v\u1ec1 t\u1edbi nh\u00e0 l\u00fac 6 gi\u1edd. <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span> ","column":2}]}],"id_ques":2517},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/vatly/bai2/lv2/img\/h1.jpg'\/><\/center>Hai xe \u00f4 t\u00f4 kh\u1edfi h\u00e0nh c\u00f9ng m\u1ed9t l\u00fac t\u1eeb hai \u0111\u1ecba \u0111i\u1ec3m A v\u00e0 B, c\u00f9ng \u0111i v\u1ec1 C (h\u00ecnh v\u1ebd). Bi\u1ebft v\u1eadn t\u1ed1c xe \u0111i t\u1eeb A l\u00e0 40 km\/h, v\u1eadn t\u1ed1c xe \u0111i t\u1eeb B l\u00e0 30 km\/h. Kho\u1ea3ng c\u00e1ch gi\u1eefa hai xe sau khi chuy\u1ec3n \u0111\u1ed9ng sau 2h l\u00e0: ","select":["A. 20 km","B. 20,5 km","C. 30 km","D. 40 km"],"hint":"","explain":"<span class='basic_left'>Nh\u00ecn v\u00e0o h\u00ecnh v\u1ebd ta th\u1ea5y \u0111o\u1ea1n \u0111\u01b0\u1eddng AB d\u00e0i l\u00e0: 108 - 67,5 = 40,5 (km). <br\/>Sau 2h, xe xu\u1ea5t ph\u00e1t t\u1eeb A \u0111i \u0111\u01b0\u1ee3c l\u00e0 : $40 \\times 2 = 80 km$<br\/>Sau 2h, xe xu\u1ea5t ph\u00e1t t\u1eeb B \u0111i \u0111\u01b0\u1ee3c l\u00e0 : $30 \\times 2 = 60 km$<br\/> V\u1eady kho\u1ea3ng c\u00e1ch gi\u1eefa 2 xe l\u00e0: $(60+40,5) - 80 = 20,5 km$.<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span> ","column":2}]}],"id_ques":2518},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/vatly/bai2/lv2/img\/h1.jpg'\/><\/center>Hai xe \u00f4 t\u00f4 kh\u1edfi h\u00e0nh c\u00f9ng m\u1ed9t l\u00fac t\u1eeb hai \u0111\u1ecba \u0111i\u1ec3m A v\u00e0 B, c\u00f9ng \u0111i v\u1ec1 C (h\u00ecnh v\u1ebd). Bi\u1ebft v\u1eadn t\u1ed1c xe \u0111i t\u1eeb A l\u00e0 40 km\/h. \u0110\u1ec3 hai xe c\u00f9ng \u0111\u1ebfn C m\u1ed9t l\u00fac th\u00ec v\u1eadn t\u1ed1c c\u1ee7a xe \u0111i t\u1eeb B l\u00e0:","select":["A. 40,5km\/h.","B. 2,7h.","C. 25km\/h.","D. 25m\/s."],"hint":"","explain":"<span class='basic_left'>Th\u1eddi gian xe A \u0111i t\u1eeb A \u0111\u1ebfn C l\u00e0:<br\/>$\\dfrac{108}{40} = 2,7$ (gi\u1edd)<br\/>V\u1eady xe B ph\u1ea3i chuy\u1ec3n \u0111\u1ed9ng v\u1edbi v\u1eadn t\u1ed1c \u0111\u1ec3 2 xe \u0111\u1ebfn C c\u00f9ng m\u1ed9t l\u00fac:<br\/>$\\dfrac{67,5}{2,7} = 25$ ($km\/h$) <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 C.<\/span><\/span> ","column":2}]}],"id_ques":2519}],"lesson":{"save":0,"level":2}}