Một chất điểm dao động điều hòa trên trục Ox theo phương trình x = 5cos4πt (x tính bằng cm, t tính bằng s). Tại thời điểm t = 5 s, vận tốc của chất điểm này có giá trị bằng

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Một số câu hỏi khác có thể bạn quan tâm.

• Choose the best answer for the following sentence:

  Since 1980, scientists all over the world ________________ a lot of things to fight against AIDS.

    

• Choose the best answer for the following sentence:

  At present, they ___________________ with the medicines to cure this terrible disease.
   

• Choose the best answer for the following sentence:

  Many people __________________ of malaria, smallpox, before the process of
  vaccination was invented in the 19^th century.
   

• Choose the best answer for the following sentence:

  Our government ___________________ a system of private schools in the new future.
   

• Choose the best answer for the following sentence:

  The doctor said that his appetite ____________________ him restore his health quickly.
   

• Choose the best answer for the following sentence:

  Now my sister _____________________ a bicycle of her own.
   

• Choose the best answer for the following sentence:

  Before the Prime Minister leaves Hanoi, he ________________ several talks.
   

• Choose the best answer for the following sentence:

  We had just got out of the car when it ____________________ to set fire.
    

• Choose the best answer for the following sentence:

  A ban was given ___________ all trade in ivory in 1989.

• Choose the best answer for the following sentence:

  John, as well as I, ___________________ a student.