ai giúp mik , mik vô 5 sao và trả lời hay nhất Biết 5 lít cát có khối lượng 7,5 kg a) Tính thể tích của 7,5 tấn cát? b) Tính trọng lượng của một đống cát có thể tích 1,5 m³? bài6Pha 80 g muối vào 0,7 lít nước. Hãy tìm khối lượng riêng của nước muối (giả sử khi hòa tan muối vào nước, thể tích nước muối tăng không đáng kể)?

1 câu trả lời

Đáp án:

\(\begin{array}{l}
5.\\
a.\\
V' = 50{m^3}\\
b.\\
P = 22500N\\
6.\\
D = 11114,286kg/{m^3}
\end{array}\)

Giải thích các bước giải:

\(\begin{array}{l}
5.\\
a.\\
D = \frac{m}{V} = \frac{{7,5}}{{{{5.10}^{ - 3}}}} = 1500kg/{m^3}\\
V' = \frac{{m'}}{D} = \frac{{75000}}{{1500}} = 50{m^3}\\
b.\\
m = V.D = 1,5.1500 = 2250kg\\
P = 10m = 2250.10 = 22500N
\end{array}\)

6.

thể tích nước:\(0,7l = 0,{7.10^{ - 3}}{m^3}\)

khối lượng của 0,7l nước:\(m = 1000.0,{7.10^{ - 3}} = 0,7kg\)

khối lượng của nước muối:M=0,7+0,08=0,78kg

khối lượng riêng của nước muối:\(D = \frac{M}{V} = \frac{{0,78}}{{0,{{7.10}^{ - 3}}}} = 11114,286kg/{m^3}\)

Câu hỏi trong lớp Xem thêm

1. Chọn đáp án thích hợp nhất (A, B, C hoặc D) để hoàn thành mỗi câu sau

11. Jane never stays up late but Bill……………….

A. does B. doesn’t C. is D. are

12. Bill: “What a lovely house you have!” John: “………………”

A. No problem! B. I think so C. That’s right D. Thanks. Hope you’ll drop in

13. This papaya is green. It is not ………………..

A. cooked B. yellow C. good D. ripe

14. There is a ………………. behind my house.

A. big beautiful flower garden B. garden flower big beautiful

C. beautiful big flower garden D. big beautiful garden flower

15. Some people play video games at home. ……………….. play them in arcades.

A. Other B. Others C. Another D. Each other

16. What ……………….. awful weather! It’s so cold and wet.

A. a B. an C. the D. 

17. My tooth doesn’t stop hurting. I’ll go and see the ………………..

A. doctor B. teacher C. dentist D. actor

18. I …………… it difficult to learn English well.

A. make B. find C. feel D. get

19. A friend of ……………….. is going to visit me next week.

A. my B. I C. mine D. me

20. Many people can write poems, but only ……………….. can be

come good poets.

A. afew B. few C. a little D. little

21. Washington D.C is ………………. capital of ………………. United States.

A., the B. the,  C. the, the D. , 

22. Marie Curie learnt to read and wrtie ................................. she was four years old.

A. while B. as soon soon C. when D. why

23. The shirts here are ................................. more expensive than those at the bookshop on the corner.

A. very B. quite C. extremely D. much

24. ................................. ruler is this? Mine or yours?

A. Who’s B. Whose C. Who D. Which

25. We can learn more about the undersea world ................................ Costeau’s invention of the diving vessel.

A. because B. because of C. thanks to D. thanks for

GIÚP MIK MIK SẼ VOTE 5 SAO VÀ CHO HAY NHẤT CHO BẠN LM ĐẦU TIÊN

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VII. Read the passage. Then answer the questions. (1.0 point) Mai and Hoa are students. They live in Viet Nam. There are four seasons in a year in their country. They are spring, summer, fall and winter. In the spring, the weather is usually warm. Sometimes it is cold, but not very cold. There are many flowers in this season. After spring, it is the summer. In the summer, the days are long and the nights are short. They often go on vacation in the summer. Fall is a nice season. The weather is often cool. In the winter, it is usually very cold. The days are short and the nights are long. They always wear warm clothes in the winter. Questions: 1. How many seasons are there in their country? What are they? =>……………..……………………………………………………………………………………… 2. What is the weather like in the spring? =>………………..…………………………………………………………………………………… 3. What do they often do in the summer? =>…………………..………………………………………………………………………………… 4. Are the days long or short in the winter? =>………………..…………………………………………………………………………………… 5. Why do they always wear warm clothes in the winter? =>………………..……………………………………………………………………………………

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