C. V= CỌR\ D V= CỌR.
1.Khoanh tron trudc dap an ma em lua chgn (Chu y: mdi cdu chi duac
lua chgn mgt đp dn).
Cau 1. Mdt vat rin cd dang hlnh cau dac đng chat ban kinh R - 0,5m quay
diu quanh true quay di qua tam vdi tdc đ gdc bing 50rad/s. Ddng
nang cua vat rin bing 1257. Khd'i lupng cua vat rin nhan gia tri nao trong cac gia tri sau
Ạ 0,5kg. B. \kg. C. \,5kg. D. 2kg.
Cau 2. Phat bilu nao dudi day diing ?
Vi tri khd'i tam ciia mdt vat phu thudc vao 1) dang hlnh hpc cua vat rin.
2) phan bd khd'i lupng trong vat rin. 3) khd'i lupng cua vat rin.
Ạ chi I). B. chi 2). C. c a i ) lin 2). D. chi 3).
Cau 3. Mdt ngudi ngoi tren mdt chiec ghe quay, hai tay cam hai qua ta gidng nhau de trudc nguc ; khi dang quay ngudi ay dang tay ra, neu bd qua ma sat anh hudng dén su quay thi chuyin đng quay se
Ạ dimg laị B. quay nhanh len. C. khdng thay đị D. quay cham laị
Cau 4. Hai vat rin cd ciing mdmen quan tinh va cd đng nang lien he vdi
nhau theo bieu thiic W^ = 2W^ . Kei luan nao sau day diing khi ndi vl
tdc dp gdc cua hai vat rin ?
3 2 D . CO] =0)2. Ạ C. 6 ^ _ 2 CO2 =6)2
Cau 5. Mdt vat rin cd mdmen quan tinh 2kg.m^ quay vdi tdc dp gdc \00rad/s. Ddng nang quay ciia vat rin la
Ạ 2007. B. 100007. C. 400/. D. 20000J. Cau 6. Dan vi nao khdng phai la don vi ciia van tdc gdc.
Ạ vdng/giay (vg/s). B. met/giay (m/s). C. vdng/phiit (vg/min). D. radian/giay (rad/s).
Cau 7. Tdng mdmen đng lupng cua vat rin dupc b i o toan khi tdng mdmen luc tac dung vao vat rin bing
Ạ hing sd. B. vd cimg. C. mdt sd bit kị D. khdng.
Cau 8. Mdt banh xe quay cham din diu quanh mdt true cd dinh vdi van tdc
gdc ban diu la 1,5rad/s. Sau 2s banh xe dirng lai, gia tdc gdc ciia xe la
Ạ 3 rad/s^ B.4,\5rad/s'
C. 3,25rad/s^ D. 3,15rad/s^
Cau 9. Bilu thiic nao trong cac bilu thiic sau day bilu diln dinh luat bao toan mdmen đng lupng ciia he vat cd mdmen quan tinh thay đi ?
A . I\CO]= l2(02-
C.^ = ^
CO, &>2
CO] CO2
D . 1]C0] = I2CO2.
Cau 10. Mdt vdng du quay ban kfnh 4m dang quay diu vdi van tdc gdc 1,5;T (adsbygoogle = window.adsbygoogle || []).push({});
rad/s. Gia tdc cua ngudi đ la
Ạ 80,5m/s^ B. 88,7m/s^
..2 r . ^ ^ . , 2
C. 78,6m/s D. 90,3m/s' Cau 11. Luc d l lam quay canh cua (Hinh ve) dupc dat
tai dilm M lin lupt theo cac phuong 1, 2, 3, 4 ;
cac phuang nay cung nim trong mat phing
vudng gdc vdi canh cuạ OM la giao tuyen cua
Cho biei : 0 M 3 < OMl = 90° < 0 M 4 < 0 M 2 . Luc se cd cudng dp nhd nhit khi dat theo
Ạ phuong 1. B. phuang 3. C. phuang 4. D. phuang 2.
Cau 12. Mdt vat rin dang quay nhanh din diu quanh mdt true ed dinh xuyen qua vat thi
Ạ tich van tdc gdc va gia tdc gdc la mdt sd am. B. gia tdc gdc ludn ludn cd gia tri duong.
C. tfch van tdc gdc va gia tdc gdc la mdt so duang. D. van tdc gdc ludn cd gia tri duong.
Cau 13. Mdt vat rin cd mdmen quan tinh đ'i vdi mdt true la /. Vat rin dang
quay vdi van tdc gdc o) quanh true quay đ. Coi ma sat d true quay
la khdng dang kl. Néu tdc dp gdc cua vat tang len 2 lin thi đng nang cua vat
Ạ tang len 2 lin. B. tang len 4 lan. C. giam 2 lin. D. khdng thay đị
Cau 14. Hai vat rin ed ciing mdmen quan tinh va cd đng nang lien he vdi
nhau theo bilu thirc W^ = 2W^ Kit luan nao sau day diing khi ndi
vl tdc dp gdc cua hai vat rin ?
CO] _ a>2 Ạ 2 = 0)2. 3 2 D . CO] -C02-
Cau 15. Hai thanh gd va thep cd kich thudc nhu nhau dupc ghep vdi nhau nhu hinh ve Gpi mdmen quan tinh đ'i vdi true A trong trudng hop a la 7^, trong trudng hpp b) la 7^. Nhan xet nao diing ?
Ạ 7« > 7^.
B. 7, < h
a) Go Thep
C. 1, = It.
D. khdng so sanh dupe vi thieu dilu kien.
Cau 16. Mdt dTa trdn đng chat cd khd'i lupng m = \kg quay diu vdi tdc dp gdc CO = 6rad / s quanh mdt true vudng gdc vdi dTa va di qua tam cua
dTạ Ddng nang cua dTa bing 97. Ban kinh cua dTa la Ạ R = l , O m . B. R = l , 3 m . C. R = 1 . 4 m . D. R = l , 5 m . H - B A I TAP T U LUAN
Bai 1. Mdt vat rin bit dau quanh nhanh din diu quanh mdt true cd dinh, sau
6s nd quay dupc mdt gdc bing 36 rad. (adsbygoogle = window.adsbygoogle || []).push({});
a) Tinh gia tdc gdc ciia banh xẹ
b) Tinh toa dp gdc va tdc dp gdc ciia banh xe d thdi diem t = 10s tinh
tir liic bit dau quaỵ
c) Vilt phuang trinh va ve đ thi bilu diln su phu thudc cua toa dp gdc ciia vat rin theo thdi gian.
Bai 2. Cho hai thanh hinh hop chii nhat cd kich thudc hinh hpc nhu nhau, mdt thanh dupc lam tir gd, thanh kia tir thep ; mdi thanh diu đng chai
Ngudi ta ghep chiing lai vdi nhau thanh mdt thanh ; O,, 02 ^i tam ciia mdi thanh. Khd'i tam cua thanh ghep nim P
G6 Thep
DAFAND^2
I - BAI TAP TRAC N G H I E M 1. Cau hdi nhieu lua chon
Cau Cau 1 B 9 A 2 C 10 B 3 D 11 A 4 C 12 C 5 B 13 B 6 B 14 C 7 D 15 A 8 D 16 A
n - B A I TAP T U LUAN
Bai 1. Chpn md'c thdi gian r = 0 tai thdi dilm vat rin bit diu quay, toa dp gdc
ban dau cpQ = 0. Chpn chilu duong la chilu quay ciia vat rin.
a) Tinh gia tdc gdc
1 2
- Ap dung cdng thirc : cp = cpQ +0)^1 + —yt, trong đ cpQ = 0 , vi van ran bat diu quay nen tdc dp gdc ban dau COQ = 0.
1 2
Suy ra : cp- — yt
2cp 2.36 2 7 = —r- = —— = 2rad / s .
t^ 6^
b) Tinh toa dp gdc va tdc dp gdc ciia banh xe d thdi dilm sau khi quay dupc 10s
- T a c d cp = -yt'^ =-.2.10^ =\00rad. 2' 2
- Tdc đ gdc dupc xac dinh: co = coQ + yt = 0 + 2.\0 = 20rad/s.
c) Phuang trinh bilu diln sir phu thudc ciia toa đ gdc cua vat rin theo
1 2
thdi gian cd dang cp = cpQ+ coQt + — yt Mat khac(PQ=0, COQ=0 va theo
2 2 ^^'^^'^^
cau a) ta cd y = 2rad / s suy ra ^ = / - Do thi bilu diln sir phu thudc ciia toa
dp gdc cua vat rin theo thdi gian chinh la đ thi cua ham sd cp = t^ do thi ham sd la nira nhinh parabol di qua gdc toa dp nhu hinh vẹ
t ( s ) (adsbygoogle = window.adsbygoogle || []).push({});
Bai 2. Tren doan 0]02 nim ben thanh thep.
Hai thanh gd va thep diu la hlnh hop chir nhat kfch thudc nhu nhau, mdi thanh diu đng chat nen khd'i tam eiia mdi thanh la giao dilm ciia dudng cheo cac hinh hop.
01 : la khd'i tam cua thanh gd ;
Chpn true toa dp la Ox di qua O, va O2. Dat 00]= x thi hoanh dp khd'i
tam ciia he thanh ghep la :
X,= ỴmjXj _ mjjr + m2.3x _ xim^ + 3m2) Sm,- mj + m2 mj + mj = X 1 + 2m2 mi + m2 X^ = X 1 + 2VP2 ViPl +P2) = X 1 + 2/>2 P1+P2
Oo yfh = 7800)tg/m^ ; p , = SOOkg/m^ nen 2,8A: < A;. < 3jf Do đ X(. nim tren doan 0 , 0 2 âen thanh thep.