Tóm tắt:

\(D=7800kg/m^3\)

\(V=40dm^3=0,04m^3\)

______________________

\(P=?\)

Giải:

Khối lượng của thanh sắt là:

\(m=D.V=7800.0,04=312\left(kg\right)\)

Trọng lượng của thanh sắt là:

\(P=10m=10.312=3120\left(N\right)\)

Vậy trọng lượng của thanh sắt là 3120 N

Dear Anna,

I have received your letter and I feel so glad when knowing that you had passed your examinations with good marks. You want me to tell you about my own family. I got married eight years ago. And now I have two sons, they are very studious, my first son is five years old. His name is Khanh. My second son is 3 years old, his name is khiem. My wife is an accountant, She is 35 years old, her name is Doan. My family lives in a small house in thai nguyen city. At the weekend, my family often goes to visit our parents. Sometimes, we stay at home and clean the house. Now I am preparing for my master entrance examination.it is very hard for me but I try my best, to pass the exam.

I have told you something about my own family life. How about your family life? Are you ready to let me know about it? I am really excited to hear about it.

Best wishes to you,

Vy