B\u00e0i 21 : Chuy\u1ec3n \u0111\u1ed9ng t\u1ecbnh ti\u1ebfn c\u1ee7a v\u1eadt r\u1eafn. Chuy\u1ec3n \u0111\u1ed9ng quay c\u1ee7a v\u1eadt r\u1eafn quanh m\u1ed9t tr\u1ee5c c\u1ed1 \u0111\u1ecbnh<\/h2>\n\n\n\n

C1<\/strong> (trang 111 sgk V\u1eadt L\u00fd 10): Chuy\u1ec3n \u0111\u1ed9ng c\u1ee7a nh\u1eefng v\u1eadt sau \u0111\u00e2y c\u00f3 ph\u1ea3i l\u00e0 chuy\u1ec3n \u0111\u1ed9ng t\u1ecbnh ti\u1ebfn kh\u00f4ng? T\u1ea1i sao?<\/p>\n\n\n\n

–\tChuy\u1ec3n \u0111\u1ed9ng c\u1ee7a b\u00e8 n\u1ee9a tr\u00ean m\u1ed9t \u0111o\u1ea1n s\u00f4ng th\u1eb3ng.<\/ins><\/p>\n\n\n\n

–\tChuy\u1ec3n \u0111\u1ed9ng c\u1ee7a ng\u01b0\u1eddi ng\u1ed3i trong chi\u1ebfc \u0111u \u0111ang quay (H\u00ecnh 21.3).<\/p>\n\n\n\n

Tr\u1ea3 l\u1eddi:<\/strong><\/p>\n\n\n\n

Chuy\u1ec3n \u0111\u1ed9ng c\u1ee7a b\u00e8 n\u1ee9a tr\u00ean s\u00f4ng l\u00e0 chuy\u1ec3n \u0111\u1ed9ng t\u1ecbnh ti\u1ebfn th\u1eb3ng.\n<\/p>\n\n\n\n

Chuy\u1ec3n \u0111\u1ed9ng c\u1ee7a l\u1ed3ng (gh\u1ebf ng\u1ed3i) c\u1ee7a ng\u01b0\u1eddi ng\u1ed3i trong chi\u1ebfc \u0111u \u0111ang quay l\u00e0 chuy\u1ec3n \u0111\u1ed9ng t\u1ecbnh ti\u1ebfn cong.\n<\/p>\n\n\n\n

V\u00ec c\u1ea3 hai chuy\u1ec3n \u0111\u1ed9ng tr\u00ean \u0111\u1ec1u th\u1ecfa m\u00e3n \u0111\u1ecbnh ngh\u0129a chuy\u1ec3n \u0111\u1ed9ng t\u1ecbnh \nti\u1ebfn: chuy\u1ec3n \u0111\u1ed9ng trong \u0111\u00f3 \u0111\u01b0\u1eddng th\u1eb3ng n\u1ed1i hai \u0111i\u1ec3m b\u1ea5t k\u00ec c\u1ee7a v\u1eadt lu\u00f4n \nsong song v\u1edbi ch\u00ednh n\u00f3.\n<\/ins><\/p>\n\n\n\n

C2<\/strong> (trang 112 sgk V\u1eadt L\u00fd 10): T\u1ea1i sao khi hai v\u1eadt c\u00f3 tr\u1ecdng l\u01b0\u1ee3ng b\u1eb1ng nhau th\u00ec r\u00f2ng r\u1ecdc v\u1eabn \u0111\u1ee9ng y\u00ean sau khi th\u1ea3 tay?<\/p>\n\n\n\n

Tr\u1ea3 l\u1eddi:<\/strong><\/p>\n\n\n\n

L\u1ef1c c\u0103ng d\u00e2y T_{1<\/sub> g\u00e2y ra m\u1ed9t momen l\u1ef1c l\u00e0m quay r\u00f2ng r\u1ecdc\n<\/p>\n\n\n\n}

L\u1ef1c c\u0103ng d\u00e2y T_{1<\/sub> g\u00e2y ra m\u1ed9t momen l\u1ef1c l\u00e0m quay r\u00f2ng r\u1ecdc b\u1eb1ng v\u1edbi momen l\u1ef1c c\u0103ng d\u00e2y T1<\/sub> g\u00e2y ra\n<\/p>\n\n\n\n}

Momen l\u1ef1c to\u00e0n ph\u1ea7n: M = (T_{1<\/sub> \u2013 T2<\/sub>).R\n<\/p>\n\n\n\n}

N\u1ebfu hai v\u1eadt c\u00f3 tr\u1ecdng l\u01b0\u1ee3ng b\u1eb1ng nhau \u21d2 T_{1<\/sub> = T2<\/sub>\n<\/p>\n\n\n\n}

\u2192 T\u1ed5ng momen l\u1ef1c b\u1eb1ng kh\u00f4ng \u2192 R\u00f2ng r\u1ecdc kh\u00f4ng quay. \n<\/p>\n\n\n\n

C3<\/strong> (trang 113 sgk V\u1eadt L\u00fd 10): \u0110o th\u1eddi gian chuy\u1ec3n \u0111\u1ed9ng c\u1ee7a v\u1eadt 1 cho \u0111\u1ebfn khi ch\u1ea1m s\u00e0n (g\u1ecdi l\u00e0 t_{o<\/sub>). <\/p>\n\n\n\n}

Tr\u1ea3 l\u1eddi:<\/strong><\/p>\n\n\n\n

H\u1ecdc sinh d\u00f9ng \u0111\u1ed3ng h\u1ed3 \u0111o th\u1eddi gian chuy\u1ec3n \u0111\u1ed9ng c\u1ee7a v\u1eadt 1 cho \u0111\u1ebfn khi ch\u1ea1m s\u00e0n \u1ee9ng v\u1edbi \u0111\u1ed9 cao h c\u1ee7a 1 v\u1eadt cho tr\u01b0\u1edbc.<\/p>\n\n\n\n

C4<\/strong> (trang 113 sgk V\u1eadt L\u00fd 10): \u0110o th\u1eddi gian chuy\u1ec3n \u0111\u1ed9ng t_{1<\/sub> c\u1ee7a m\u1ed9t v\u1eadt cho t\u1edbi khi ch\u1ea1m s\u00e0n. So s\u00e1nh t1<\/sub> v\u1edbi to<\/sub> r\u1ed3i r\u00fat ra k\u1ebft lu\u1eadn v\u1ec1 m\u1ee9c qu\u00e1n t\u00ednh c\u1ee7a v\u1eadt.<\/p>\n\n\n\n}

Tr\u1ea3 l\u1eddi:<\/strong><\/p>\n\n\n\n

N\u1ebfu t_{1<\/sub> < to<\/sub> th\u00ec t\u1ed1c \u0111\u1ed9 g\u00f3c c\u1ee7a r\u00f2ng r\u1ecdc t\u0103ng nhanh h\u01a1n \u1ee9ng v\u1edbi kh\u1ed1i l\u01b0\u1ee3ng c\u1ee7a r\u00f2ng r\u1ecdc nh\u1ecf h\u01a1n.\n<\/p>\n\n\n\n}

\u2192 M\u1ee9c qu\u00e1n t\u00ednh c\u1ee7a m\u1ed9t v\u1eadt quay quanh m\u1ed9t tr\u1ee5c ph\u1ee5 thu\u1ed9c v\u00e0o kh\u1ed1i l\u01b0\u1ee3ng c\u1ee7a v\u1eadt.\n<\/ins><\/p>\n\n\n\n

C5<\/strong> (trang 113 sgk V\u1eadt L\u00fd 10): \u0110o th\u1eddi gian chuy\u1ec3n \u0111\u1ed9ng t_{2<\/sub> c\u1ee7a v\u1eadt 1 cho t\u1edbi khi ch\u1ea1m s\u00e0n, so s\u00e1nh v\u1edbi to<\/sub> \u0111\u1ec3 r\u00fat ra k\u1ebft lu\u1eadn v\u1ec1 m\u1ee9c qu\u00e1n t\u00ednh c\u1ee7a v\u1eadt.<\/p>\n\n\n\n}

Tr\u1ea3 l\u1eddi:<\/strong><\/p>\n\n\n\n

– N\u1ebfu t_{2<\/sub> < to<\/sub>, t\u1ed1c \u0111\u1ed9 g\u00f3c c\u1ee7a r\u00f2ng r\u1ecdc t\u0103ng nhanh h\u01a1n \u1ee9ng v\u1edbi s\u1ef1 ph\u00e2n b\u1ed1 kh\u1ed1i l\u01b0\u1ee3ng g\u1ea7n tr\u1ee5c quay h\u01a1n.\n<\/p>\n\n\n\n}

– Ng\u01b0\u1ee3c l\u1ea1i: s\u1ef1 ph\u00e2n b\u1ed1 kh\u1ed1i l\u01b0\u1ee3ng xa tr\u1ee5c quay h\u01a1n, ch\u1ee7 y\u1ebfu \u1edf v\u00e0nh ngo\u00e0i th\u00ec t\u1ed1c \u0111\u1ed9 g\u00f3c c\u1ee7a r\u00f2ng r\u1ecdc t\u0103ng ch\u1eadm h\u01a1n, t_{2<\/sub> > to<\/sub>.\n<\/p>\n\n\n\n}

\u2192 M\u1ee9c qu\u00e1n t\u00ednh c\u1ee7a m\u1ed9t v\u1eadt quay quanh m\u1ed9t tr\u1ee5c ph\u1ee5 thu\u1ed9c v\u00e0o s\u1ef1 ph\u00e2n b\u1ed1 kh\u1ed1i l\u01b0\u1ee3ng \u0111\u00f3 \u0111\u1ed1i v\u1edbi tr\u1ee5c quay. <\/p>\n\n\n\n

B\u00e0i 5 (trang 114 SGK V\u1eadt L\u00fd 10) :<\/strong> M\u1ed9t v\u1eadt\n c\u00f3 kh\u1ed1i l\u01b0\u1ee3ng m = 40 kg b\u1eaft \u0111\u1ea7u tr\u01b0\u1ee3t tr\u00ean s\u00e0n nh\u00e0 d\u01b0\u1edbi t\u00e1c d\u1ee5ng c\u1ee7a \nm\u1ed9t l\u1ef1c n\u1eb1m ngang F = 200 N. H\u1ec7 s\u1ed1 ma s\u00e1t tr\u01b0\u1ee3t gi\u1eefa v\u1eadt v\u00e0 s\u00e0n l\u00e0 \u00b5_{t<\/sub>=0,25. H\u00e3y t\u00ednh:<\/ins><\/p>\n\n\n\n}

a)\tGia t\u1ed1c c\u1ee7a v\u1eadt;<\/p>\n\n\n\n

b)\tV\u1eadn t\u1ed1c c\u1ee7a v\u1eadt \u1edf cu\u1ed1i gi\u00e2y th\u1ee9 ba;<\/p>\n\n\n\n

c)\t\u0110o\u1ea1n \u0111\u01b0\u1eddng m\u00e0 v\u1eadt \u0111i \u0111\u01b0\u1ee3c trong 3 gi\u00e2y \u0111\u1ea7u. L\u1ea5y g = 10 m\/s^{2<\/sup>.<\/p>\n\n\n\n}

L\u1eddi gi\u1ea3i:<\/strong><\/p>\n\n\n\n

<\/figure>\n\n\n\n

a)\tC\u00e1c l\u1ef1c t\u00e1c d\u1ee5ng l\u00ean v\u1eadt \u0111\u01b0\u1ee3c bi\u1ec3u di\u1ec5n nh\u01b0 h\u00ecnh v\u1ebd. Ch\u1ecdn tr\u1ee5c Ox v\u00e0 Oy nh\u01b0 h\u00ecnh v\u1ebd.\n<\/p>\n\n\n\n

\u00c1p d\u1ee5ng \u0111\u1ecbnh lu\u1eadt II Niu \u2013 t\u01a1n: \n<\/p>\n\n\n\n

<\/figure>\n\n\n\n

Chi\u1ebfu (1) l\u00ean Ox ta \u0111\u01b0\u1ee3c: F_{k<\/sub> \u2013 Fms<\/sub> = ma (2)\n<\/p>\n\n\n\n}

Chi\u1ebfu (1) l\u00ean Oy ta \u0111\u01b0\u1ee3c: N \u2013 P = 0 (3)\n<\/p>\n\n\n\n

(theo tr\u1ee5c Oy gia t\u1ed1c c\u1ee7a v\u1eadt b\u1eb1ng 0 do v\u1eadt kh\u00f4ng chuy\u1ec3n \u0111\u1ed9ng theo ph\u01b0\u01a1ng \u0111\u00f3)\n<\/p>\n\n\n\n

T\u1eeb (2) v\u00e0 (3) ta \u0111\u01b0\u1ee3c: \n<\/p>\n\n\n\n

<\/figure>\n\n\n\n

b) V\u1eadn t\u1ed1c c\u1ee7a v\u1eadt \u1edf cu\u1ed1i gi\u00e2y th\u1ee9 ba: v = v_{0<\/sub> + at = 0 + 2,5.3 = 7,5 m\/s.\n<\/p>\n\n\n\n}

c) \u0110o\u1ea1n \u0111\u01b0\u1eddng m\u00e0 v\u1eadt \u0111i \u0111\u01b0\u1ee3c trong 3 gi\u00e2y \u0111\u1ea7u:\n<\/p>\n\n\n\n

<\/figure>\n\n\n\n

B\u00e0i 6 (trang 115 SGK V\u1eadt L\u00fd 10) :<\/strong> M\u1ed9t v\u1eadt\n c\u00f3 kh\u1ed1i l\u01b0\u1ee3ng m = 4,0 kg chuy\u1ec3n \u0111\u1ed9ng tr\u00ean m\u1eb7t s\u00e0n n\u1eb1m ngang d\u01b0\u1edbi t\u00e1c \nd\u1ee5ng c\u1ee7a m\u1ed9t l\u1ef1c F h\u1ee3p v\u1edbi h\u01b0\u1edbng chuy\u1ec3n \u0111\u1ed9ng m\u1ed9t g\u00f3c \u03b1 = 30^{o<\/sup> (H\u00ecnh 21.6) . H\u1ec7 s\u1ed1 ma s\u00e1t tr\u01b0\u1ee3t gi\u1eefa v\u1eadt v\u00e0 s\u00e0n l\u00e0 \u03bc_{t<\/sub> = 0,30. T\u00ednh \u0111\u1ed9 l\u1edbn c\u1ee7a l\u1ef1c \u0111\u1ec3:<\/ins><\/p>\n\n\n\n}}

a) V\u1eadt chuy\u1ec3n \u0111\u1ed9ng v\u1edbi gia t\u1ed1c b\u1eb1ng 1,25 m\/s^{2<\/sup>.<\/p>\n\n\n\n}

b) V\u1eadt chuy\u1ec3n \u0111\u1ed9ng th\u1eb3ng \u0111\u1ec1u. L\u1ea5y g = 10 m\/s^{2<\/sup>.<\/p>\n\n\n\n}

L\u1eddi gi\u1ea3i:<\/strong><\/p>\n\n\n\n

<\/figure>\n\n\n\n

a)\tC\u00e1c l\u1ef1c t\u00e1c d\u1ee5ng l\u00ean v\u1eadt \u0111\u01b0\u1ee3c bi\u1ec3u di\u1ec5n nh\u01b0 h\u00ecnh v\u1ebd. Ch\u1ecdn h\u1ec7 tr\u1ee5c Ox theo h\u01b0\u1edbng chuy\u1ec3n \u0111\u1ed9ng, Oy vu\u00f4ng g\u00f3c ph\u01b0\u01a1ng chuy\u1ec3n \u0111\u1ed9ng.\n<\/p>\n\n\n\n

\u00c1p d\u1ee5ng \u0111\u1ecbnh lu\u1eadt II Niu \u2013 t\u01a1n ta \u0111\u01b0\u1ee3c:\n<\/ins><\/p>\n\n\n\n

<\/figure>\n\n\n\n

Chi\u1ebfu h\u1ec7 th\u1ee9c vecto l\u00ean tr\u1ee5c Ox ta \u0111\u01b0\u1ee3c:\n<\/p>\n\n\n\n

Fcos\u03b1 – F_{ms<\/sub> = ma (1)\n<\/p>\n\n\n\n}

Chi\u1ebfu h\u1ec7 th\u1ee9c vecto l\u00ean tr\u1ee5c Oy ta \u0111\u01b0\u1ee3c:\n<\/p>\n\n\n\n

Fsin\u03b1 – P + N = 0 \u21d4 N = P – Fsin\u03b1 (2)\n<\/p>\n\n\n\n

M\u1eb7t kh\u00e1c F_{ms<\/sub> = \u03bct<\/sub>N = \u03bct<\/sub>(P – Fsin\u03b1) (3)\n<\/p>\n\n\n\n}

T\u1eeb (1) v\u00e0 (2) (3) suy ra:\n<\/p>\n\n\n\n

<\/figure>\n\n\n\n

b)\t\u0110\u1ec3 v\u1eadt chuy\u1ec3n \u0111\u1ed9ng th\u1eb3ng \u0111\u1ec1u (a = 0) ta c\u00f3:\n<\/p>\n\n\n\n

<\/figure>\n\n\n\n

\u21d4 Fcos\u03b1 – \u03bc_{t<\/sub>(P – Fsin\u03b1) \u21d2 F = 12(N) <\/p>\n\n\n\n}

B\u00e0i 7 (trang 115 SGK V\u1eadt L\u00fd 10) :<\/strong> M\u1ed9t xe \nca c\u00f3 kh\u1ed1i l\u01b0\u1ee3ng 1250 kg \u0111\u01b0\u1ee3c d\u00f9ng \u0111\u1ec3 k\u00e9o m\u1ed9t xe m\u00f3c c\u00f3 kh\u1ed1i l\u01b0\u1ee3ng 325 \nkg. C\u1ea3 hai xe c\u00f9ng chuy\u1ec3n \u0111\u1ed9ng v\u1edbi gia t\u1ed1c 2,15 m\/s^{2<\/sup> . B\u1ecf qua chuy\u1ec3n \u0111\u1ed9ng quay c\u1ee7a c\u00e1c b\u00e1nh xe. H\u00e3y x\u00e1c \u0111\u1ecbnh:<\/ins><\/p>\n\n\n\n}

a)\tH\u1ee3p l\u1ef1c t\u00e1c d\u1ee5ng l\u00ean xe ca;<\/p>\n\n\n\n

b)\tH\u1ee3p l\u1ef1c t\u00e1c d\u1ee5ng l\u00ean xe m\u00f3c.<\/p>\n\n\n\n

L\u1eddi gi\u1ea3i:<\/strong><\/p>\n\n\n\n

<\/figure>\n\n\n\n

a)\tC\u00e1c l\u1ef1c t\u00e1c d\u1ee5ng l\u00ean h\u1ec7 xe ca v\u00e0 xe mo\u00f3c \u0111\u01b0\u1ee3c bi\u1ec3u di\u1ec5n nh\u01b0 h\u00ecnh v\u1ebd.\n<\/p>\n\n\n\n

\u00c1p d\u1ee5ng \u0111\u1ecbnh lu\u1eadt II Niu \u2013 T\u01a1n cho xe ca ta c\u00f3:\n <\/p>\n\n\n\n

<\/figure>\n\n\n\n

Chi\u1ebfu l\u00ean chi\u1ec1u d\u01b0\u01a1ng l\u00e0 chi\u1ec1u chuy\u1ec3n \u0111\u1ed9ng, ta t\u00ecm \u0111\u01b0\u1ee3c h\u1ee3p l\u1ef1c t\u00e1c d\u1ee5ng l\u00ean xe ca l\u00e0: F_{hlA<\/sub> = mA<\/sub>. a = 1250. 2,15 = 2687,5 (N)\n<\/p>\n\n\n\n}

b) \u00c1p d\u1ee5ng \u0111\u1ecbnh lu\u1eadt II Niu \u2013 T\u01a1n cho xe mo\u00f3c ta c\u00f3:\n<\/p>\n\n\n\n

<\/figure>\n\n\n\n

Chi\u1ebfu l\u00ean chi\u1ec1u d\u01b0\u01a1ng l\u00e0 chi\u1ec1u chuy\u1ec3n \u0111\u1ed9ng, ta t\u00ecm \u0111\u01b0\u1ee3c h\u1ee3p l\u1ef1c t\u00e1c d\u1ee5ng l\u00ean xe mo\u00f3c: <\/p>\n\n\n\n

F_{hlB<\/sub> = mB<\/sub>. a = 325. 2,15 = 698,8 (N). <\/p>\n\n\n\n}

B\u00e0i 8 (trang 115 SGK V\u1eadt L\u00fd 10) :<\/strong> M\u1ed9t v\u1eadt\n \u0111ang quay quanh m\u1ed9t tr\u1ee5c v\u1edbi t\u1ed1c \u0111\u1ed9 g\u00f3c \t\u03c9\t = 6,28 rad\/s . N\u1ebfu b\u1ed7ng \nnhi\u00ean momen l\u1ef1c t\u00e1c d\u1ee5ng l\u00ean n\u00f3 \u0111\u1ed9t nhi\u00ean m\u1ea5t \u0111i th\u00ec <\/ins><\/p>\n\n\n\n

A.\tV\u1eadt d\u1eebng l\u1ea1i ngay.<\/p>\n\n\n\n

B.\tV\u1eadt \u0111\u1ed5i chi\u1ec1u quay.<\/p>\n\n\n\n

C.\tV\u1eadt quay \u0111\u1ec1u v\u1edbi t\u1ed1c \u0111\u1ed9 g\u00f3c \u03c9 = 6,28 rad\/s.<\/p>\n\n\n\n

D.\tV\u1eadt quay ch\u1eadm d\u1ea7n r\u1ed3i d\u1eebng l\u1ea1i.<\/p>\n\n\n\n

Ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang<\/p>\n\n\n\n

L\u1eddi gi\u1ea3i:<\/strong><\/p>\n\n\n\n

Ch\u1ecdn C. \n<\/p>\n\n\n\n

Do n\u00f3 c\u00f3 qu\u00e1n t\u00ednh n\u00ean khi m\u1ea5t momen l\u1ef1c v\u1eadt v\u1eabn s\u1ebd quay ti\u1ebfp v\u1edbi t\u1ed1c \u0111\u1ed9 g\u00f3c nh\u01b0 c\u0169 l\u00e0 \u03c9 = 6,28 rad\/s. <\/p>\n\n\n\n

B\u00e0i 9 (trang 115 SGK V\u1eadt L\u00fd 10) :<\/strong> \u0110\u1ed1i v\u1edbi v\u1eadt quay quanh m\u1ed9t tr\u1ee5c c\u1ed1 \u0111\u1ecbnh, c\u00e2u n\u00e0o sau \u0111\u00e2y l\u00e0 \u0111\u00fang?<\/ins><\/p>\n\n\n\n

A.\tN\u1ebfu kh\u00f4ng ch\u1ecbu momen l\u1ef1c t\u00e1c d\u1ee5ng th\u00ec v\u1eadt ph\u1ea3i \u0111\u1ee9ng y\u00ean.<\/p>\n\n\n\n

B.\tKhi kh\u00f4ng c\u00f2n momen l\u1ef1c t\u00e1c d\u1ee5ng th\u00ec v\u1eadt \u0111ang quay s\u1ebd l\u1eadp t\u1ee9c d\u1eebng l\u1ea1i.<\/p>\n\n\n\n

C.\tV\u1eadt quay \u0111\u01b0\u1ee3c l\u00e0 nh\u1edd c\u00f3 momen l\u1ef1c t\u00e1c d\u1ee5ng l\u00ean n\u00f3.<\/p>\n\n\n\n

D.\tKhi th\u1ea5y t\u1ed1c \u0111\u1ed9 g\u00f3c c\u1ee7a v\u1eadt quay \u0111\u1ed5i th\u00ec ch\u1eafc ch\u1eafn l\u00e0 n\u00f3 \u0111\u00e3 c\u00f3 momen l\u1ef1c t\u00e1c d\u1ee5ng l\u00ean v\u1eadt.<\/p>\n\n\n\n

L\u1eddi gi\u1ea3i:<\/strong><\/p>\n\n\n\n

Ch\u1ecdn D. \n<\/p>\n\n\n\n

V\u00ec momen l\u1ef1c t\u00e1c d\u1ee5ng v\u00e0o m\u1ed9t v\u1eadt quay quanh m\u1ed9t tr\u1ee5c c\u1ed1 \u0111\u1ecbnh l\u00e0m thay \u0111\u1ed5i t\u1ed1c \u0111\u1ed9 g\u00f3c c\u1ee7a v\u1eadt n\u00ean khi th\u1ea5y t\u1ed1c \u0111\u1ed9 g\u00f3c c\u1ee7a v\u1eadt thay \u0111\u1ed5i th\u00ec ch\u1eafc ch\u1eafn l\u00e0 \u0111\u00e3 c\u00f3 momen l\u1ef1c t\u00e1c d\u1ee5ng l\u00ean v\u1eadt. <\/p>\n\n\n\n

B\u00e0i 10 (trang 115 SGK V\u1eadt L\u00fd 10) :<\/strong> M\u1ee9c qu\u00e1n t\u00ednh c\u1ee7a m\u1ed9t v\u1eadt quay quanh m\u1ed9t tr\u1ee5c kh\u00f4ng ph\u1ee5 thu\u1ed9c v\u00e0o<\/p>\n\n\n\n

A.\tKh\u1ed1i l\u01b0\u1ee3ng c\u1ee7a v\u1eadt.<\/p>\n\n\n\n

B.\tH\u00ecnh d\u1ea1ng v\u00e0 k\u00edch th\u01b0\u1edbc c\u1ee7a v\u1eadt.<\/ins><\/p>\n\n\n\n

C.\tT\u1ed1c \u0111\u1ed9 g\u00f3c c\u1ee7a v\u1eadt.<\/p>\n\n\n\n

D.\tV\u1ecb tr\u00ed c\u1ee7a tr\u1ee5c quay.<\/p>\n\n\n\n

Ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang.<\/p>\n\n\n\n

L\u1eddi gi\u1ea3i:<\/strong><\/p>\n\n\n\n

Ch\u1ecdn C. \n<\/p>\n\n\n\n

M\u1ee9c qu\u00e1n t\u00ednh c\u1ee7a m\u1ed9t v\u1eadt quay quanh m\u1ed9t tr\u1ee5c ch\u1ec9 ph\u1ee5 thu\u1ed9c v\u00e0o: kh\u1ed1i\n l\u01b0\u1ee3ng c\u1ee7a v\u1eadt, h\u00ecnh d\u1ea1ng v\u00e0 k\u00edch th\u01b0\u1edbc c\u1ee7a v\u1eadt v\u00e0 v\u1ecb tr\u00ed tr\u1ee5c quay.\n<\/p>\n","protected":false},"excerpt":{"rendered":"

B\u00e0i 21 : Chuy\u1ec3n \u0111\u1ed9ng t\u1ecbnh ti\u1ebfn c\u1ee7a v\u1eadt r\u1eafn. Chuy\u1ec3n \u0111\u1ed9ng quay c\u1ee7a v\u1eadt r\u1eafn quanh m\u1ed9t tr\u1ee5c c\u1ed1 \u0111\u1ecbnh C1 (trang 111 sgk V\u1eadt L\u00fd 10): Chuy\u1ec3n \u0111\u1ed9ng c\u1ee7a nh\u1eefng v\u1eadt sau \u0111\u00e2y c\u00f3 ph\u1ea3i l\u00e0 chuy\u1ec3n \u0111\u1ed9ng t\u1ecbnh ti\u1ebfn kh\u00f4ng? T\u1ea1i sao? – Chuy\u1ec3n \u0111\u1ed9ng c\u1ee7a b\u00e8 n\u1ee9a tr\u00ean m\u1ed9t \u0111o\u1ea1n s\u00f4ng […]<\/p>\n","protected":false},"author":12,"featured_media":44151,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_mi_skip_tracking":false,"tdm_status":"","tdm_grid_status":""},"categories":[1640],"tags":[],"yoast_head":"\n