user-avatar
949011828960697
2 năm trước
Người ta dùng một mặt phẳng nghiêng để kéo một vật có khối lượng 50kg lên cao 1,5m. a) Nếu không có ma sát thì lực kéo vật là 150N. Tính chiều dài của mặt phẳng nghiêng b) Thực tế, lực ma sát giữa vật và mặt phẳng nghiêng là 30N. Tính hiệu suất của mặt phẳng nghiêng.
Thích Trả lời Chia sẻ

Các câu hỏi liên quan

31. La Tomatina is a ________ festival to celebrate the tomato harvest. A. season B. year C. seasonal D. annually 32. Alternative sources of energy ________ developed in the near future. A. will be B. has been C. is D. was 33. " ________ is it from your house to the nearest bus stop?" - "About 50 metres." A. How long B. How often C. How far D. How much 34. People living in the slums never get good healthcare ________ ? A. are they B. do they C. aren't they D. don't they 35. What should we do to ________ our electric bills? A. fall B. drop C. cut down D. reduce 36. They spent a huge amount of money on the film; ________ , it was not a big success. A. but B. because C. however D. although 37. A ________ is a film that shows real life events or stories. A. thriller B. documentary C. comedy D. action 38. There ________ a bus station in the city centre, but it has been moved to the suburbs. A. use to have B. used to have C. were D. used to be 39. Which is the best ________ of transport for the future? A. means B. ways C. mean D. traffic 40. The digital camera belongs to Nick. That camera is ________ . A. his B. one C. him D. he 41. Several governments try to ________ the use of fossil fuels. A. reduce B. waste C. increase D. save 42. With teleportation, you disappear at a place, and then ________ in another place seconds later. A. reappears B. reappear C. appeared D. appears 43. The energy consumption ________ as much as possible. A. reduced B. will be reduced C. will reduced D. be reduced 44. I could not eat ________ I was very hungry. A. despite B. even though C. in spite the fact that D. in spite 45. Diwali, the Hindu Festival of Light, is the ________ holiday of the year in India. A. importance B. most important C. most importance D. more important 46. Every day over 1,000 new cars add to the city and the city of over 20 million people is getting more and more ________ . A. famous B. expensive C. gridlocked D. difficult 47. ________ an accident in the High Street, traffic is moving very slowly on the London Road. A. Despite B. Because of C. Since D. Because 48. Cyclists and motorists have to wear a ________ when they ride a motorbike. A. hard hat B. helmet C. cap D. mask 49. Overcrowded places have a lot of problems, ________ ? A. does it B. have they C. doesn't it D. don't they 50. ________ the wet weather, the football match went ahead. A. Although B. Owing to C. In spite of D. But for 51. At this time next week, we ________ a wind turbine in our garden. A. install B. will be installing C. installed D. will installed

2018 © Loga - Không Ngừng Sáng Tạo - Bùng Cháy Đam Mê
Loga Team