Một quả cầu có khối lượng m=100g đang chuyển động với vận tốc v=10m/s thì đập vuông góc vào 1 bức tường sau đó bật ngược trở lại với cùng vận tốc 10m/s. Chọn chiều dương là chiều chuyển động ban đầu của quả cầu. a) tính độ biến thiên động lượng vật? b) tính độ lớn của tường tác dụng vào vật t gian va chạm là 0,1s?

Tóm Tắt 2 Bài Văn:Bài Học Đường Đời Đầu Tiên Và Bức Tranh Của Em Gái Tôi Nhanh lên nhé au nhanh nhất mình cho 5sao và câu trả lời hay nhất nha :)

III.CHOOSE THE MOST APPROPRIATE ANSWER TO COMPLETE THE SENTENCE BELOW 1. Trung bought some goldfish and kept them in an_______________. A. aquarium B. envelope C. river D. umbrella 2. “Thanks a lot.” – “_______________” A. You’re welcome. B. That’s right! C. That’s OK D. I’d love to. 3 Hi, Liz. Welcome back. How ……………….. your vacation in Nha Trang ? A. are B. is C. was D. were 4. We should have a medical...........................every six months. A. treatment B. record C. problem D. check-up 5. Moderation in eating is the _______to a healthy lifestyle. A. important B. key C. door D. advice 6. Most of the world’s surface is____________( land / mountains / water / rivers ) 7. Hoa feels sick. She ate too _____________candy last night. A. much B. many C. a lot of D. More 9. Do you help your parents ________________the housework? A. for B. abou C. to D. with 10. Tom likes volleyball,.........his brother doesn’t.His brother likes soccer. A.and B.so C.but D.or 12. Walking is a good sports..............It makes us ........... A.game-healthy B.game-health C.activity-healthy D.activity-health 13. Driving fast in a big city is very_______________. A. happy B. easy C. dangerous D. careless 14. He explained the words ____________, but they did not understand at all. A. clear B.hardly C. bad D. clearly 15. She _________ the beef thinly before stir-frying it in a little vegetable oil. A. boiled B. sliced C. added D. cooked 16“_______________” – “I feel terrible.” A. What would you like to do? B. Why didn’t you go to school yesterday? C. What was wrong with you? D. What’s the matter? 17. _____________ to have dinner at my house? – Yes. I’d love to. A. Do you like B. Would you like C What about D. Should We 18. What was ____________ with her ? A. matter B. problem C. wrong D. symptom 20. Don’t forget ……………….. off the lights before going out. A. to turn B. turned C. turning D. turn 21. Every day, I get up early to ………………. morning exercises. A. do B. make C. take D. A & C are correct 22 We can learn more about the undersea thanks ………………………… this invention. A. in B. on C. of D. to 23. The medicines you take only relieve the ________. A. temperature B. cold C. symptoms D. cure 24. Don’t eat this durian. It’s not _________________. a. good b. green c. ripe d. cool 26. ........... is a condition of the body when it is too hot because of illness. A. Cold B. Fever C. Cough D. Flu 27. I’d like _________ by listening to music at breaktime. A. relaxed B. relaxing C. to relax D. relax 28. “I didn’t like the film.” – “ _____________” A. We did, either. B. Neither did we. C. We didn’t, too. D. So did we. 30. I ‘ve got a headache.-................................................ A.You must take some medicine B.You mustn’t stay in bed C.You ought to stay up late D.You shouldn’t take a rest A B C IV. Complete the passage, using the words given in the box any, far, new, years, from, by, live, in, with, motorbike Lan is our (1)______ classmate. She comes (2) _____ Nha Trang. She is (3) ____ class 7A. She is thirteen (4) _____ old. Her parents (5) ______ in Nha Trang. Now she’s living (6) _____ her aunt and uncle in HCM city. Her house is (7) ____ from school. So, she usually goes to school (8)____ bus. a. Cleaning floor day. b. Caution wet floor. c. Wet floor ahead. d. Keeping out of floor 29. Khang and I _________ swim when we were only five years old. A. should B. could C. can D. must IV. Complete the passage, using the words given in the box any, far, new, years, from, by, live, in, with, motorbike Lan is our (1)______ classmate. She comes (2) _____ Nha Trang. She is (3) ____ class 7A. She is thirteen (4) _____ old. Her parents (5) ______ in Nha Trang. Now she’s living (6) _____ her aunt and uncle in HCM city. Her house is (7) ____ from school. So, she usually goes to school (8)____ bus. Sometimes, her aunt takes her to school by (9) _______. She doesn’t have (10) _____ friends. So she feels sad. V. Write in the correct order to have meaningful sentence 1. on/ may/ Lan/ be/ will/ Sunday/ 25th/ 13. …………………………………………………………… 2. Call/ six/ will/ I/ after/ o’ clock/ again/her. …………………………………………………………… 3. speak/ can/?/ I/ Van/ to/ please. …………………………………………………………… 4. you/ free/ morning/ be/ will/ tomorrow/? …………………………………………………………… 5. parents/ Thu/ with/ in/ lives/ Hanoi/ her. ……………………………………………………………

một vườn trường hình chữ nhật có chiều dài gấp 3 lần chiều rộng . Nếu tăng chiều dài thêm 2m và giảm chiều rộng lên 3m thì diện tích vường trường giảm đi 90m2. tính diện tích lúc đầu

anh chị giúp em với ạ em đang cần gấp

hai thua ruong thu hoach duoc 4 tan thoc 3 ta thoc . biet rang thua ruong thu nhat thu hoach duoc it hon thua ruong thu hai 3 ta thoc . hoi thua ruong thu hoach duoc bao nhieu ta thoc ?

cho a,b là hai stn lớn hơn 1 A. a.b là số nguyên tố C.a-b là số ntố B.a+b là số nguyên tố D.cả ba câu ở trên đều sai ai lm đc mik vote 5 sao

Tìm số nguyên x biết : 25 - |3 - x|=10

Giúp mình với ạ Làm cả 2 bài thì càng tốt ạ

bạn nào ko giải được hết đừng giải nhé mà thêm vào phần bình luận của các bạn đã giải hết nhé II. Choose the best answer. 1. What ____ the matter with you? A. Are. B. Is. C. do. D. does. 2. Mai ______ a stomach ache. A. Have. B. haves. C. Has D. does. 3. I ______ a toothache. A. Have. B. has. C. do. D. am. 4. Nam ___ a headache last night. A. Has. B. Have. C. had. D. does. 5. Quan ___ to the dentist yesterday because he ___ a toothache. A. Went- has. B. go- have. C. goes- has D. went- had. 6. Today, Lan ____ go to school because she ____ a fever. A. Can- is. B. can’t – has. C. can’t – is. D. should- has. 7. I think you should ____ a rest. A. take. B. go. C. do. D. does. 8. She shouldn’t _____ heavy things because you has a backache. A. Take B. lift C. carries. D. do. 9. I _____ speak becacause I has a _____. A. Cannot- sore throat. B. can- throat. C. should- sore throat. D. A&C. 10. Linda____ feel well. A. don’t B. doesn’t. C. isn’t. D. Does. 11. Yesterday, I ___ too much, so I had a stomach ache. A. Ate. B. eat. C. eats. D. eated. 12. I will __him go to the doctor after breakfast. A. go. B. send. C. Take. D. should 13. Quan’s grandparents ___ a backache. A. Has. B have. C. Are. D. take. 14. Phong has a ___ because he is in high temperature. A. Fever. B. sore throat. C. cut. D. runny noes. 15. Mai can’t come __ class today. A. for B. with. C. at. D. to. 16. Some students __ not ___ school. A. is- in. B. are- in. C. is- at. D. are-at. 17. Peter ___ go to school yesterday because He had a stomach ache. A. Doesn’t B. shouldn’t C. didn’t D. couldn’t 18. Mai has a ___ toothache, so she went to the dentist last Sunday. A. Bad. B. good. C. well. D. very hot 19. You ____ do morning excersise everyday to stay healthy. A. Can B. will C. can’t D. should. 20. He’s ___ home. A. in B. on C. at D. with