{"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":"Trong c\u00e1c tr\u01b0\u1eddng h\u1ee3p n\u00e0o sau \u0111\u00e2y, tr\u01b0\u1eddng h\u1ee3p n\u00e0o n\u00f3i \u0111\u1ebfn v\u1eadn t\u1ed1c trung b\u00ecnh?","select":["A. S\u1ed1 ch\u1ec9 v\u1eadn t\u1ed1c c\u1ee7a xe m\u00e1y \u0111\u1ecdc \u0111\u01b0\u1ee3c tr\u00ean \u0111\u1ed3ng h\u1ed3 v\u1eadn t\u1ed1c (c\u00f4ng t\u01a1 m\u00e9t) c\u1ee7a xe l\u00e0 45km\/h.","B. V\u1eadn t\u1ed1c c\u1ee7a v\u1eadt chuy\u1ec3n \u0111\u1ed9ng \u0111\u1ec1u l\u00e0 v = 4m\/s.","C. V\u1eadn t\u1ed1c c\u1ee7a v\u1eadt khi qua m\u1ed9t v\u1ecb tr\u00ed x\u00e1c \u0111\u1ecbnh n\u00e0o \u0111\u00f3 l\u00e0 12m\/s.","D. V\u1eadn t\u1ed1c c\u1ee7a xe \u00f4 t\u00f4 ch\u1ea1y tr\u00ean qu\u00e3ng \u0111\u01b0\u1eddng TP HCM \u0111i Long An l\u00e0 45km\/h."],"hint":"","explain":"<span class='basic_left'>V\u1eadn t\u1ed1c c\u1ee7a xe \u00f4 t\u00f4 ch\u1ea1y tr\u00ean qu\u00e3ng \u0111\u01b0\u1eddng TP HCM \u0111i Long An l\u00e0 45km\/h. V\u00ec v\u1eadn t\u1ed1c trung b\u00ecnh l\u00e0 v\u1eadn t\u1ed1c tr\u00ean c\u1ea3 m\u1ed9t \u0111o\u1ea1n \u0111\u01b0\u1eddng ho\u1eb7c trong m\u1ed9t kho\u1ea3ng th\u1eddi gian c\u1ee5 th\u1ec3. <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 D.<\/span><\/span> ","column":1}]}],"id_ques":2520},{"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":"Quan s\u00e1t chuy\u1ec3n \u0111\u00f4\u0323ng c\u1ee7a tr\u1ee5c b\u00e1nh xe \u0111ang l\u0103n xu\u1ed1ng m\u1eb7t ph\u1eb3ng nghi\u00eang. Chuy\u1ec3n \u0111\u1ed9ng c\u1ee7a tr\u1ee5c b\u00e1nh xe l\u00e0 chuy\u1ec3n \u0111\u1ed9ng c\u00f3 t\u00ednh ch\u1ea5t g\u00ec? Ch\u1ecdn ph\u01b0\u01a1ng \u00e1n tr\u1ea3 l\u1eddi \u0111\u00fang trong c\u00e1c ph\u01b0\u01a1ng \u00e1n sau:","select":["A. Chuy\u1ec3n \u0111\u1ed9ng \u0111\u1ec1u.","B. Chuy\u1ec3n \u0111\u1ed9ng c\u00f3 v\u1eadn t\u1ed1c t\u0103ng d\u1ea7n.","C. Chuy\u1ec3n \u0111\u1ed9ng c\u00f3 v\u1eadn t\u1ed1c gi\u1ea3m d\u1ea7n.","D. Chuy\u1ec3n \u0111\u1ed9ng c\u00f3 v\u1eadn t\u1ed1c v\u1eeba t\u0103ng v\u1eeba gi\u1ea3m."],"hint":"","explain":"<span class='basic_left'>Tr\u1ee5c b\u00e1nh xe \u0111ang l\u0103n xu\u1ed1ng m\u1eb7t ph\u1eb3ng nghi\u00eang.<br\/>\u21d2 Chuy\u1ec3n \u0111\u1ed9ng c\u1ee7a tr\u1ee5c b\u00e1nh xe l\u00e0 chuy\u1ec3n \u0111\u1ed9ng c\u00f3 v\u1eadn t\u1ed1c t\u0103ng d\u1ea7n.<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span> ","column":1}]}],"id_ques":2521},{"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":"M\u1ed9t ng\u01b0\u1eddi \u0111i xe \u0111\u1ea1p xu\u1ed1ng m\u1ed9t c\u00e1i d\u1ed1c d\u00e0i 120m h\u1ebft 30s. Khi h\u1ebft d\u1ed1c, xe l\u0103n ti\u1ebfp m\u1ed9t qu\u00e3ng \u0111\u01b0\u1eddng n\u1eb1m ngang d\u00e0i 60m trong 24s r\u1ed3i d\u1eebng l\u1ea1i. V\u1eadn t\u1ed1c trung b\u00ecnh tr\u00ean m\u1ed7i \u0111o\u1ea1n \u0111\u01b0\u1eddng c\u00f3 th\u1ec3 nh\u1eadn gi\u00e1 tr\u1ecb n\u00e0o trong c\u00e1c gi\u00e1 tr\u1ecb sau?","select":["A. ${{v}_{1}}$ = 4m\/s v\u00e0 ${{v}_{2}}$ = 2,5m\/s.","B. M\u1ed9t c\u1eb7p gi\u00e1 tr\u1ecb kh\u00e1c.","C. ${{v}_{1}}$ = 2,5m\/s v\u00e0 ${{v}_{2}}$ = 5m\/s.","D. ${{v}_{1}}$ = 4,5m\/s v\u00e0 ${{v}_{2}}$ = 2m\/s."],"hint":"","explain":"<span class='basic_left'>Ta c\u00f3: v\u1eadn t\u1ed1c trung b\u00ecnh c\u1ee7a xe \u0111\u1ea1p l\u00e0:<br\/>Tr\u00ean \u0111o\u1ea1n \u0111\u01b0\u1eddng d\u1ed1c: ${{v}_{1}}=\\dfrac{{{S}_{1}}}{{{t}_{1}}}=\\dfrac{120}{30}=4m\/s$ <br\/>Tr\u00ean \u0111o\u1ea1n \u0111\u01b0\u1eddng n\u1eb1m ngang: ${{v}_{2}}=\\dfrac{{{S}_{2}}}{{{t}_{2}}}=\\dfrac{60}{24}=2,5m\/s$ <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 A.<\/span><\/span> ","column":2}]}],"id_ques":2522},{"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":"M\u1ed9t m\u00e1y bay ch\u1edf h\u00e0nh kh\u00e1ch bay gi\u1eefa hai th\u00e0nh ph\u1ed1 A v\u00e0 B. Khi xu\u00f4i gi\u00f3 th\u1eddi gian bay l\u00e0 1h30ph, c\u00f2n khi ng\u01b0\u1ee3c gi\u00f3 th\u1eddi gian bay l\u00e0 1h45ph. Bi\u1ebft v\u1eadn t\u1ed1c gi\u00f3 lu\u00f4n kh\u00f4ng \u0111\u1ed5i l\u00e0 10 m\/s. V\u1eadn t\u1ed1c c\u1ee7a m\u00e1y bay l\u00fac kh\u00f4ng c\u00f3 gi\u00f3 l\u00e0:","select":["A. 468 km\/h.","B. 648 km\/h.","C. 684 km\/h.","D. T\u1ea5t c\u1ea3 c\u00e1c ph\u01b0\u01a1ng \u00e1n \u0111\u1ec1u sai."],"hint":"","explain":"<span class='basic_left'>G\u1ecdi v\u1eadn t\u1ed1c c\u1ee7a m\u00e1y bay l\u00e0 v, th\u1eddi gian l\u00fac xu\u00f4i gi\u00f3 l\u00e0 ${{t}_{1}}$ <br\/>V\u1eadn t\u1ed1c c\u1ee7a gi\u00f3 l\u00e0 vg, th\u1eddi gian l\u00fac ng\u01b0\u1ee3c gi\u00f3 l\u00e0 ${{t}_{2}}$ <br\/>Do qu\u00e3ng \u0111\u01b0\u1eddng c\u1ee7a m\u00e1y bay l\u00fac xu\u00f4i gi\u00f3 v\u00e0 ng\u01b0\u1ee3c gi\u00f3 l\u00e0 b\u1eb1ng nhau n\u00ean ta c\u00f3:<br\/> ${{t}_{1}}\\times \\left( v+vg \\right)={{t}_{2}}\\times \\left( v-vg \\right)$ <br\/>Suy ra: $\\dfrac{{{t}_{1}}}{{{t}_{2}}}=\\dfrac{v-vg}{v+vg}$<br\/> N\u00ean ta c\u00f3: $\\dfrac{5400}{6300}=\\dfrac{v-10}{v+10}$<br\/>Hay ta c\u00f3: 900v =6300+5400= 11700 suy ra v=130m\/s=468km\/h.<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 A.<\/span><\/span> ","column":2}]}],"id_ques":2523},{"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":"M\u1ed9t v\u1eadn \u0111\u1ed9ng vi\u00ean b\u1eafn s\u00fang b\u1eafn m\u1ed9t ph\u00e1t \u0111\u1ea1n v\u00e0o bia c\u00e1ch ch\u1ed7 ng\u01b0\u1eddi \u0111\u00f3 \u0111\u1ee9ng l\u00e0 330 m. Th\u1eddi gian t\u1eeb l\u00fac b\u1eafn \u0111\u1ebfn l\u00fac ng\u01b0\u1eddi \u0111\u00f3 nghe th\u1ea5y ti\u1ebfng \u0111\u1ea1n n\u1ed5 l\u00e0 1,6s. Bi\u1ebft v\u1eadn t\u1ed1c truy\u1ec1n \u00e2m trong kh\u00f4ng kh\u00ed l\u00e0 330 m\/s. Th\u1eddi gian t\u1eeb l\u00fac b\u1eafn \u0111\u1ebfn l\u00fac \u0111\u1ea1n tr\u00fang bia l\u00e0: ","select":["A. 0.5s","B. 0.8s","C. 0.4s","D. 0.6s"],"hint":"","explain":"<span class='basic_left'>Th\u1eddi gian t\u1eeb l\u00fac \u0111\u1ea1n tr\u00fang bia \u0111\u1ebfn tai v\u1eadn \u0111\u1ed9ng vi\u00ean l\u00e0:<br\/>${{t}_{2}}=\\dfrac{s}{v}=\\dfrac{330}{330}=1m\/s$ <br\/>V\u1eady th\u1eddi gian t\u1eeb l\u00fac b\u1eafn cho \u0111\u1ebfn l\u00fac \u0111\u1ea1n tr\u00fang bia l\u00e0: <br\/>${{t}_{1}}=t-{{t}_{2}}=1,6-1=0,6s$<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 D.<\/span><\/span> ","column":2}]}],"id_ques":2524},{"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 \u0111i qu\u00e3ng \u0111\u01b0\u1eddng ${{S}_{1}}$ v\u1edbi v\u1eadn t\u1ed1c ${{v}_{1}}$ h\u1ebft ${{t}_{1}}$ gi\u00e2y, \u0111i qu\u00e3ng \u0111\u01b0\u1eddng ti\u1ebfp theo ${{S}_{2}}$ v\u1edbi v\u1eadn t\u1ed1c ${{v}_{2}}$ h\u1ebft ${{t}_{2}}$ gi\u00e2y. D\u00f9ng c\u00f4ng th\u1ee9c n\u00e0o \u0111\u1ec3 t\u00ednh v\u1eadn t\u1ed1c trung b\u00ecnh c\u1ee7a ng\u01b0\u1eddi n\u00e0y tr\u00ean c\u1ea3 hai qu\u00e3ng \u0111\u01b0\u1eddng ${{S}_{1}}$ v\u00e0 ${{S}_{2}}$ ?","select":["A. ${{v}_{tb}}$ = (${{v}_{1}}$ +${{v}_{2}}$ )\/2.","B. ${{v}_{tb}}$ = (${{S}_{1}}$ +${{S}_{2}}$ )\/(${{t}_{1}}$ +${{t}_{2}}$ ).","C. ${{v}_{tb}}$ = ${{v}_{1}}$ \/${{S}_{1}}$ +${{v}_{2}}$ \/${{S}_{2}}$ .","D. C\u1ea3 ba c\u00f4ng th\u1ee9c tr\u00ean \u0111\u1ec1u kh\u00f4ng \u0111\u00fang."],"hint":"","explain":"<span class='basic_left'>V\u1eadn t\u1ed1c trung b\u00ecnh b\u1eb1ng t\u1ed5ng qu\u00e3ng \u0111\u01b0\u1eddng \u0111i \u0111\u01b0\u1ee3c chia cho t\u1ed5ng th\u1eddi gian \u0111i:<br\/>${{v}_{tb}}$ = (${{S}_{1}}$ +${{S}_{2}}$ )\/(${{t}_{1}}$ +${{t}_{2}}$ ) <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span> ","column":2}]}],"id_ques":2525},{"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":"K\u1ec9 l\u1ee5c th\u1ebf gi\u1edbi v\u1ec1 ch\u1ea1y 100m do l\u1ef1c s\u0129 Tim \u2014 ng\u01b0\u1eddi M\u0129 \u2014 \u0111\u1ea1t \u0111\u01b0\u1ee3c l\u00e0 9,86 gi\u00e2y. T\u00ednh v\u1eadn t\u1ed1c trung b\u00ecnh c\u1ee7a v\u1eadn \u0111\u1ed9ng vi\u00ean n\u00e0y ra km\/h?","select":["A. 31,9km\/h.","B. 52,7km\/h.","C. 23,3km\/h.","D. 36,8km\/h."],"hint":"","explain":"<span class='basic_left'>V\u1eadn t\u1ed1c trung b\u00ecnh b\u1eb1ng t\u1ed5ng qu\u00e3ng \u0111\u01b0\u1eddng \u0111i \u0111\u01b0\u1ee3c chia cho t\u1ed5ng th\u1eddi gian \u0111i:<br\/>${{v}_{tb}}=\\dfrac{S}{t}=10,22m\/s=36,8km\/h$<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 D.<\/span><\/span> ","column":2}]}],"id_ques":2526},{"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":"Chuy\u1ec3n \u0111\u1ed9ng n\u00e0o sau \u0111\u00e2y l\u00e0 chuy\u1ec3n \u0111\u1ed9ng \u0111\u1ec1u? ","select":["A. V\u1eadn \u0111\u1ed9ng vi\u00ean tr\u01b0\u1ee3t tuy\u1ebft t\u1eeb d\u1ed1c n\u00fai xu\u1ed1ng.","B. V\u1eadn \u0111\u1ed9ng vi\u00ean ch\u1ea1y 100m \u0111ang v\u1ec1 \u0111\u00edch.","C. M\u00e1y bay bay t\u1eeb H\u00e0 N\u1ed9i v\u00e0o TP H\u1ed3 Ch\u00ed Minh.","D. Kh\u00f4ng c\u00f3 chuy\u1ec3n \u0111\u1ed9ng n\u00e0o k\u1ec3 tr\u00ean l\u00e0 chuy\u1ec3n \u0111\u1ed9ng \u0111\u1ec1u."],"hint":"","explain":"<span class='basic_left'>T\u1ea5t c\u1ea3 c\u00e1c chuy\u1ec3n \u0111\u1ed9ng tr\u00ean \u0111\u1ec1u c\u00f3 s\u1ef1 thay \u0111\u1ed5i v\u1eadn t\u1ed1c trong qu\u00e1 tr\u00ecnh chuy\u1ec3n \u0111\u1ed9ng.<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 D.<\/span><\/span> ","column":1}]}],"id_ques":2527},{"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 \u0111i xe \u0111\u1ea1p \u0111i n\u1eeda qu\u00e3ng \u0111\u01b0\u1eddng \u0111\u1ea7u v\u1edbi v\u1eadn t\u1ed1c ${{v}_{1}}$ = 12km\/h, n\u1eeda c\u00f2n l\u1ea1i v\u1edbi v\u1eadn t\u1ed1c ${{v}_{2}}$ n\u00e0o \u0111\u00f3. Bi\u1ebft v\u1eadn t\u1ed1c trung b\u00ecnh tr\u00ean c\u1ea3 qu\u00e3ng \u0111\u01b0\u1eddng l\u00e0 8km\/h. H\u00e3y t\u00ednh v\u1eadn t\u1ed1c ${{v}_{2}}$.","select":["A. 5km\/h.","B. 6km\/h.","C. 7km\/h.","D. 8km\/h."],"hint":"","explain":"<span class='basic_left'>G\u1ecdi s l\u00e0 chi\u1ec1u d\u00e0i n\u1eeda qu\u00e3ng \u0111\u01b0\u1eddng <br\/>Th\u1eddi gian \u0111i h\u1ebft n\u1eeda qu\u00e3ng \u0111\u01b0\u1eddng \u0111\u1ea7u v\u1edbi v\u1eadn t\u1ed1c ${{v}_{1}}$ l\u00e0: ${{t}_{1}}=\\dfrac{s}{{{v}_{1}}}$ (1)<br\/>Th\u1eddi gian \u0111i h\u1ebft n\u1eeda qu\u00e3ng \u0111\u01b0\u1eddng c\u00f2n l\u1ea1i v\u1edbi v\u1eadn t\u1ed1c ${{v}_{2}}$ l\u00e0: ${{t}_{2}}=\\dfrac{s}{{{v}_{2}}}$ (2)<br\/>V\u1eadn t\u1ed1c trung b\u00ecnh c\u1ee7a ng\u01b0\u1eddi \u0111i xe \u0111\u1ea1p tr\u00ean qu\u00e3ng \u0111\u01b0\u1eddng l\u00e0 $\\dfrac{2s}{{{t}_{1}}+{{t}_{2}}}$ (3)<br\/>K\u1ebft h\u1ee3p (1); (2); (3) v\u00e0 thay s\u1ed1 ${{v}_{tb}}$ = 8km\/h; ${{v}_{1}}$ = 12km\/h. <br\/> V\u1eadn t\u1ed1c trung b\u00ecnh c\u1ee7a ng\u01b0\u1eddi \u0111i xe \u1edf n\u1eeda qu\u00e3ng \u0111\u01b0\u1eddng sau l\u00e0 ${{v}_{2}}$ = 6km\/h <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span> ","column":2}]}],"id_ques":2528},{"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 v\u1eadt chuy\u1ec3n \u0111\u1ed9ng kh\u00f4ng \u0111\u1ec1u. Bi\u1ebft v\u1eadn t\u1ed1c trung b\u00ecnh c\u1ee7a v\u1eadt trong 1\/3 th\u1eddi gian \u0111\u1ea7u b\u1eb1ng 12m\/s; trong th\u1eddi gian c\u00f2n l\u1ea1i b\u1eb1ng 9m\/s. V\u1eadn t\u1ed1c trung b\u00ecnh c\u1ee7a v\u1eadt trong su\u1ed1t th\u1eddi gian chuy\u1ec3n \u0111\u1ed9ng l\u00e0? ","select":["A. 10,5m\/s.","B. 10m\/s.","C. 9,8m\/s.","D. 11 m\/s."],"hint":"","explain":"<span class='basic_left'>Ta c\u00f3:<br\/>${{S}_{1}}={{v}_{1}}\\times {{t}_{1}}=12\\times \\dfrac{t}{3}=4t$<br\/> ${{S}_{2}}={{v}_{2}}\\times {{t}_{2}}=9\\times \\dfrac{2t}{3}=6t$<br\/>${{v}_{tb}}=\\dfrac{{{s}_{1}}+{{s}_{2}}}{t}=\\dfrac{10t}{t}=10m\/s$<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span> ","column":2}]}],"id_ques":2529},{"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":"H\u00e0 N\u1ed9i c\u00e1ch \u0110\u1ed3 S\u01a1n 120km. M\u1ed9t \u00f4t\u00f4 r\u1eddi H\u00e0 N\u1ed9i \u0111i \u0110\u1ed3 S\u01a1n v\u1edbi v\u1eadn t\u1ed1c 45km\/h. M\u1ed9t ng\u01b0\u1eddi \u0111i xe \u0111\u1ea1p v\u1edbi v\u1eadn t\u1ed1c 15km\/h xu\u1ea5t ph\u00e1t c\u00f9ng l\u00fac theo h\u01b0\u1edbng ng\u01b0\u1ee3c l\u1ea1i t\u1eeb \u0110\u1ed3 S\u01a1n v\u1ec1 H\u00e0 N\u1ed9i. Sau bao l\u00e2u \u00f4t\u00f4 v\u00e0 xe \u0111\u1ea1p g\u1eb7p nhau?","select":["A. 1h","B. 2h","C. 3h","D. 4h"],"hint":"","explain":"<span class='basic_left'>Sau 1 gi\u1edd \u00f4t\u00f4 v\u00e0 xe \u0111\u1ea1p g\u1ea7n nhau 1 kho\u1ea3ng:<br\/> v = ${{v}_{1}}$ + ${{v}_{2}}$ = 60km\/h<br\/> V\u1eady \u0111\u1ec3 \u0111i h\u1ebft 120km th\u00ec m\u1ea5t th\u1eddi gian: $t=\\dfrac{120}{{{v}_{1}}+{{v}_{2}}}=2h$ <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span> ","column":2}]}],"id_ques":2530},{"time":24,"part":[{"title":"","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/vatly/bai3/lv2/img\/h0.jpg'\/><\/center>Th\u1ea3 vi\u00ean bi tr\u00ean m\u00e1ng nghi\u00eang v\u00e0 m\u00e1ng ngang nh\u01b0 h\u00ecnh v\u1ebd. Ph\u00e1t bi\u1ec3u n\u00e0o d\u01b0\u1edbi \u0111\u00e2y ch\u01b0a ch\u00ednh x\u00e1c?","select":["A. Vi\u00ean bi chuy\u1ec3n \u0111\u1ed9ng nhanh d\u1ea7n t\u1eeb A \u0111\u1ebfn B.","B. Vi\u00ean bi chuy\u1ec3n \u0111\u1ed9ng ch\u1eadm d\u1ea7n t\u1eeb B \u0111\u1ebfn C.","C. Vi\u00ean bi chuy\u1ec3n \u0111\u1ed9ng nhanh d\u1ea7n t\u1eeb A \u0111\u1ebfn C.","D. Vi\u00ean bi chuy\u1ec3n \u0111\u1ed9ng kh\u00f4ng \u0111\u1ec1u tr\u00ean \u0111o\u1ea1n AC."],"hint":"","explain":"<span class='basic_left'>Tr\u00ean \u0111oan AC, vi\u00ean bi chuy\u1ec3n \u0111\u1ed9ng kh\u00f4ng \u0111\u1ec1u. AB nhanh d\u1ea7n, BC ch\u1eadm d\u1ea7n.<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 C.<\/span><\/span> ","column":1}]}],"id_ques":2531},{"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 ng\u01b0\u1eddi \u0111i xe m\u00e1y t\u1eeb A \u0111\u1ebfn B c\u00e1ch nhau 400m. N\u1eeda qu\u00e3ng \u0111\u01b0\u1eddng \u0111\u1ea7u, xe \u0111i v\u1edbi v\u1eadn t\u1ed1c ${{v}_{1}}$ , n\u1eeda qu\u00e3ng \u0111\u01b0\u1eddng sau xe \u0111i tr\u00ean c\u00e1t n\u00ean v\u1eadn t\u1ed1c ${{v}_{2}}$ ch\u1ec9 b\u1eb1ng n\u1eeda v\u1eadn t\u1ed1c ${{v}_{1}}$ . H\u00e3y t\u00ednh ${{v}_{1}}$ \u0111\u1ec3 ng\u01b0\u1eddi \u0111\u00f3 \u0111i t\u1eeb A \u0111\u1ebfn B trong 1 ph\u00fat.","select":["A. 5m\/s.","B. 40km\/h.","C. 10 m\/s.","D. 36km\/h."],"hint":"","explain":"<span class='basic_left'>Th\u1eddi gian \u0111i n\u1eeda \u0111o\u1ea1n \u0111\u01b0\u1eddng \u0111\u1ea7u l\u00e0: ${{t}_{1}}=\\dfrac{200}{{{v}_{1}}}$<br\/>Th\u1eddi gian \u0111i n\u1eeda \u0111o\u1ea1n \u0111\u01b0\u1eddng \u0111\u1ea7u l\u00e0: ${{t}_{2}}=\\dfrac{200}{\\left( \\dfrac{{{v}_{1}}}{2} \\right)}$<br\/>T\u1ed5ng th\u1eddi gian \u0111i l\u00e0: ${{t}_{1}}+{{t}_{2}}=\\dfrac{200}{{{v}_{1}}}+\\dfrac{200}{\\left( \\dfrac{{{v}_{1}}}{2} \\right)}$ = 60s<br\/>T\u00ednh ra ta \u0111\u01b0\u1ee3c: ${{v}_{1}}=10m\/s$ <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 A.<\/span><\/span> ","column":2}]}],"id_ques":2532},{"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":"Trong c\u00e1c chuy\u1ec3n \u0111\u1ed9ng sau, chuy\u1ec3n \u0111\u1ed9ng n\u00e0o l\u00e0 \u0111\u1ec1u: ","select":["A. Chuy\u1ec3n \u0111\u1ed9ng c\u1ee7a qu\u1ea3 d\u1eeba r\u01a1i t\u1eeb tr\u00ean c\u00e2y xu\u1ed1ng.","B. Chuy\u1ec3n \u0111\u1ed9ng c\u1ee7a M\u1eb7t Tr\u0103ng quanh Tr\u00e1i \u0110\u1ea5t.","C. Chuy\u1ec3n \u0111\u1ed9ng c\u1ee7a \u0111\u1ea7u c\u00e1ch qu\u1ea1t.","D. Chuy\u1ec3n \u0111\u1ed9ng c\u1ee7a xe bu\u00fdt t\u1eeb Th\u1ee7y Ph\u00f9 l\u00ean Hu\u1ebf."],"hint":"","explain":"<span class='basic_left'>Chuy\u1ec3n \u0111\u1ed9ng c\u1ee7a M\u1eb7t Tr\u0103ng quanh Tr\u00e1i \u0110\u1ea5t l\u00e0 chuy\u1ec3n \u0111\u1ed9ng tr\u00f2n \u0111\u1ec1u.<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span> ","column":1}]}],"id_ques":2533},{"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":"\u0110\u00e0o \u0111i b\u1ed9 t\u1eeb nh\u00e0 t\u1edbi tr\u01b0\u1eddng, qu\u00e3ng \u0111\u01b0\u1eddng \u0111\u1ea7u d\u00e0i 200m \u0110\u00e0o \u0111i m\u1ea5t 1ph\u00fat 40s; qu\u00e3ng \u0111\u01b0\u1eddng c\u00f2n l\u1ea1i d\u00e0i 300m \u0110\u00e0o \u0111i m\u1ea5t 100s. V\u1eadn t\u1ed1c trung b\u00ecnh c\u1ee7a \u0110\u00e0o tr\u00ean m\u1ed7i \u0111o\u1ea1n \u0111\u01b0\u1eddng v\u00e0 c\u1ea3 \u0111o\u1ea1n \u0111\u01b0\u1eddng l\u1ea7n l\u01b0\u1ee3t l\u00e0:","select":["A. 2m\/s; 3m\/s; 2,5m\/s.","B. 3m\/s; 2,5m\/s; 2m\/s.","C. 2m\/s; 2,5m\/s; 3m\/s.","D. 3m\/s; 2m\/s; 2,5m\/s."],"hint":"","explain":"<span class='basic_left'>${{v}_{1}}=\\dfrac{{{S}_{1}}}{{{t}_{1}}}=\\dfrac{200}{100}=2m\/s$<br\/>${{v}_{2}}=\\dfrac{{{S}_{2}}}{{{t}_{2}}}=\\dfrac{300}{100}=3m\/s$<br\/>${{v}_{tb}}=\\dfrac{S}{t}=\\dfrac{500}{200}=2,5m\/s$<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 A.<\/span><\/span> ","column":2}]}],"id_ques":2534},{"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":"T\u00e0u Th\u1ed1ng Nh\u1ea5t TN1 \u0111i t\u1eeb ga Hu\u1ebf v\u00e0o ga S\u00e0i G\u00f2n m\u1ea5t 20h. Bi\u1ebft v\u1eadn t\u1ed1c trung b\u00ecnh c\u1ee7a t\u00e0u l\u00e0 15m\/s. H\u1ecfi chi\u1ec1u d\u00e0i c\u1ee7a \u0111\u01b0\u1eddng ray t\u1eeb Hu\u1ebf v\u00e0o S\u00e0i G\u00f2n?","select":["A. 3000km.","B.1080km.","C. 1000km.","D. 1333km."],"hint":"","explain":"<span class='basic_left'>\u0110\u1ed5i 15m\/s = 54km\/h.<br\/>V\u1eady qu\u00e3ng \u0111\u01b0\u1eddng l\u00e0: 20 x 54 = 1080km.<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span> ","column":2}]}],"id_ques":2535},{"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 \u0111i xe \u0111\u1ea1p tr\u00ean \u0111o\u1ea1n \u0111\u01b0\u1eddng MNPQ. Bi\u1ebft tr\u00ean \u0111o\u1ea1n \u0111\u01b0\u1eddng MN = $s_1$ ng\u01b0\u1eddi \u0111\u00f3 \u0111i v\u1edbi v\u1eadn t\u1ed1c $v_1$, trong th\u1eddi gian $t_1$; tr\u00ean \u0111o\u1ea1n \u0111\u01b0\u1eddng NP = $s_2$ ng\u01b0\u1eddi \u0111\u00f3 \u0111i v\u1edbi v\u1eadn t\u1ed1c $v_2$, trong th\u1eddi gian $t_2$; tr\u00ean \u0111o\u1ea1n \u0111\u01b0\u1eddng PQ = $s_3$ ng\u01b0\u1eddi \u0111\u00f3 \u0111i v\u1edbi v\u1eadn t\u1ed1c $v_3$, trong th\u1eddi gian $t_3$. V\u1eadn t\u1ed1c trung b\u00ecnh c\u1ee7a ng\u01b0\u1eddi \u0111\u00f3 tr\u00ean \u0111o\u1ea1n \u0111\u01b0\u1eddng MNPQ \u0111\u01b0\u1ee3c t\u00ednh b\u1edfi c\u00f4ng th\u1ee9c:","select":["A. $v=\\dfrac{{{v}_{1}}+{{v}_{2}}+{{v}_{3}}}{3}$.","B. $v=\\dfrac{{{s}_{1}}+{{s}_{2}}+{{s}_{3}}}{{{t}_{1}}+{{t}_{2}}+{{t}_{3}}}$.","C. $v=\\dfrac{{{v}_{1}}{{t}_{1}}+{{v}_{2}}{{t}_{2}}+{{v}_{3}}{{t}_{3}}}{{{t}_{1}}+{{t}_{2}}+{{t}_{3}}}$.","D. $v=\\dfrac{\\dfrac{{{s}_{1}}}{{{t}_{1}}}+\\dfrac{{{s}_{2}}}{{{t}_{2}}}+\\dfrac{{{s}_{3}}}{{{t}_{3}}}}{3}$."],"hint":"","explain":"<span class='basic_left'>V\u1eadn t\u1ed1c trung b\u00ecnh b\u1eb1ng t\u1ed5ng qu\u00e3ng \u0111\u01b0\u1eddng \u0111i \u0111\u01b0\u1ee3c chia cho t\u1ed5ng th\u1eddi gian \u0111i.<br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span> ","column":1}]}],"id_ques":2536},{"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 ng\u01b0\u1eddi \u0111i b\u1ed9 \u0111\u1ec1u tr\u00ean qu\u00e3ng \u0111\u01b0\u1eddng \u0111\u1ea7u d\u00e0i 3km v\u1edbi v\u1eadn t\u1ed1c 2m\/s. Qu\u00e3ng \u0111\u01b0\u1eddng ti\u1ebfp theo d\u00e0i 1,95km, ng\u01b0\u1eddi \u0111\u00f3 \u0111i h\u1ebft 0,5h. T\u00ednh v\u1eadn t\u1ed1c trung b\u00ecnh c\u1ee7a ng\u01b0\u1eddi \u0111\u00f3 tr\u00ean c\u1ea3 hai qu\u00e3ng \u0111\u01b0\u1eddng.","select":["A. 3m\/s.","B. 2m\/s.","C. 1,5 m\/s.","D. 1 m\/s."],"hint":"","explain":"<span class='basic_left'>Th\u1eddi gian \u0111i h\u1ebft qu\u00e3ng \u0111\u01b0\u1eddng th\u1ee9 nh\u1ea5t:<br\/>${{t}_{1}}=\\dfrac{{{s}_{1}}}{{{v}_{1}}}=\\dfrac{3000}{2}=1500s$ <br\/>V\u1eadn t\u1ed1c trung b\u00ecnh tr\u00ean c\u1ea3 qu\u00e3ng \u0111\u01b0\u1eddng:<br\/> $v=\\dfrac{{{s}_{1}}+{{s}_{2}}}{{{t}_{1}}+{{t}_{2}}}=\\dfrac{3000+1950}{1500+1800}=1,5m\/s$ <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 C.<\/span><\/span> ","column":2}]}],"id_ques":2537},{"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 tr\u1eadn \u0111\u1ea5u gi\u1eefa \u0110\u1ee9c v\u00e0 \u00c1o \u1edf EURO 2008, Ti\u1ec1n v\u1ec7 Mai-C\u01a1n BaLack c\u1ee7a \u0111\u1ed9i tuy\u1ec3n \u0110\u1ee9c s\u00fat ph\u1ea1t c\u00e1ch khung th\u00e0nh c\u1ee7a \u0111\u1ed9i \u00c1o 30m. C\u00e1c chuy\u00ean gia t\u00ednh \u0111\u01b0\u1ee3c v\u1eadn t\u1ed1c trung b\u00ecnh c\u1ee7a qu\u1ea3 \u0111\u00e1 ph\u1ea1t \u0111\u00f3 l\u00ean t\u1edbi 108km\/h. H\u1ecfi th\u1eddi gian b\u00f3ng bay?","select":["A. 1s","B. 36s","C. 1,5s","D. 3,6s"],"hint":"","explain":"<span class='basic_left'>\u0110\u1ed5i 108km\/h = 30 m\/s. Th\u1eddi gian b\u00f3ng bay l\u00e0: $t=\\dfrac{30}{30}=1s$ <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 A.<\/span><\/span> ","column":2}]}],"id_ques":2538},{"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 chi\u1ebfc can\u00f4 \u0111i d\u1ecdc m\u1ed9t con s\u00f4ng t\u1eeb A \u0111\u1ebfn B m\u1ea5t h\u1ebft 2h v\u00e0 \u0111i ng\u01b0\u1ee3c h\u1ebft 3h. H\u1ecfi ng\u01b0\u1eddi \u0111\u00f3 t\u1eaft m\u00e1y \u0111\u1ec3 cho ca n\u00f4 tr\u00f4i theo d\u00f2ng n\u01b0\u1edbc t\u1eeb A \u0111\u1ebfn B m\u1ea5t bao l\u00e2u?","select":["A. 5h.","B. 6h.","C. 12h.","D. Kh\u00f4ng th\u1ec3 t\u00ednh \u0111\u01b0\u1ee3c."],"hint":"","explain":"<span class='basic_left'>G\u1ecdi v\u1eadn t\u1ed1c ca n\u00f4 l\u00e0 $v_1$, g\u1ecdi v\u1eadn t\u1ed1c c\u1ee7a n\u01b0\u1edbc l\u00e0 $v_2$.<br\/>Khi \u0111i xu\u00f4i d\u00f2ng, ta c\u00f3: ${{S}_{AB}}=({{v}_{1}}+{{v}_{2}})\\times 2$<br\/>Khi \u0111i ng\u01b0\u1ee3c d\u00f2ng, ta c\u00f3: ${{S}_{AB}}=({{v}_{1}}-{{v}_{2}})\\times 3$<br\/>T\u1eeb \u0111\u00f3 t\u00ednh \u0111\u01b0\u1ee3c: ${{v}_{2}}=\\dfrac{1}{12}{{S}_{AB}}$<br\/>V\u1eady th\u1eddi gian \u0111\u1ec3 \u0111i ng\u01b0\u1ee3c d\u00f2ng l\u00e0:$\\dfrac{{S}_{AB}}{{v}_{2}}=12h$ <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 C.<\/span><\/span> ","column":2}]}],"id_ques":2539}],"lesson":{"save":0,"level":2}}