Hai lò xo giống nhau có cùng độ cứng 10N/m. Mắc hai lò xo song song nhau rồi treo vật nặng khối lượng khối lượng m = 200g. Lấy \(\pi ^2 = 10\). Chu kỳ dao động tự do của hệ là:

Chia sẻ

Một số câu hỏi khác có thể bạn quan tâm.

• Read the passage below and choose one correct answer for each question:

           We had the marathon today. A dozen of us sped off. People stood on the streets, cheering us on. It was like we were in the Olympics. Peter was ahead of me. So was Owen. Then I shot off. I was racing ahead. My legs were going faster than the rest of me. I sped off onto the main road and kept running past other runners until there was only Peter left in front of me. On and on, I ran. My legs and lungs were hurting but I couldn't stop. Just outside the town, I ran past Peter. A minute later, I was declared the winner of the marathon. Everyone cheered and clapped. It was hot. I was perspiring. I could hardly breathe but it didn't matter. I felt like a hero.

   

  1. How many students took part in the marathon?
  A. There were many students.                  B. There were a few.
  C. There were ten.                                    D. There were twelve.

  2. At first the writer ran ___________.
  A. very fast
  B. very slowly
  C. as quickly as his friend, Peter
  D. more slowly than his friends, Peter and Owen

  3. After a long distance of running, he felt _________ .
  A. very strong              B. very tired                  C. very excited                D. happy
  
  4. He ran past over Peter _______________ .
  A. after some minutes
  B. outside of the town
  C. inside the town
  D. after a minute

  5. He was declared _________________.
  A. the hero of the marathon
  B. the winner of the marathon
  C. the strongest of the marathon
  D. the healthy man of the marathon

   

   

   

• Find a mistake in the four underlined parts of the sentence and correct it:

  My father was thinking of buy a new computer for me.

• Find a mistake in the four underlined parts of the sentence and correct it:

  This scientific theory has now been proved be false.

• Find a mistake in the four underlined parts of the sentence and correct it:

  Having achieved highest score, our team was rewarded the first prize.

• Find a mistake in the four underlined parts of the sentence and correct it:

  Having achieved highest score, our team was rewarded the first prize.

• Find a mistake in the four underlined parts of the sentence and correct it:

  When I kept to get unwanted calls, I had my phone number changed.

• Choose the best answer for the following sentence:

  Up to now I have never forgot the most embarrassing experience ________________ .

   

   

• Choose the best answer for the following sentence:

  _______________________ when I began to learn English.

   

• Choose the best answer for the following sentence:

  _______________________ I would not have overcome my mispronunciation.

   

   

• Choose a word that has different stress pattern:

  inadequate            embarrassment                dispirited             entertainment