Một xe chuyển động nhanh dần đều với vận tốc ban đầu 4 m/s. Trong giây thứ 3 xe đi được 5 m. Tính quãng đường xe đi được trong 10 s?
Một xe chuyển động nhanh dần đều với vận tốc ban đầu 4 m/s. Trong giây thứ 3 xe đi được 5 m. Tính quãng đường xe đi được trong 10 s?
Hãy suy nghĩ và trả lời câu hỏi trước khi xem đáp án
Quãng đường xe đi được sau $t$ giây là $s = v_0t + \frac{1}{2}at^2$.
Quãng đường xe đi được sau $2$ giây là $s_2 = v_0(2) + \frac{1}{2}a(2)^2 = 8 + 2a$.
Quãng đường xe đi được sau $3$ giây là $s_3 = v_0(3) + \frac{1}{2}a(3)^2 = 12 + \frac{9}{2}a$.
Quãng đường xe đi được trong giây thứ 3 là $s_3 - s_2 = 5$, suy ra $(12 + \frac{9}{2}a) - (8 + 2a) = 5$, hay $4 + \frac{5}{2}a = 5$, suy ra $\frac{5}{2}a = 1$, vậy $a = \frac{2}{5} = 0.4$ m/s$^2$.
Quãng đường xe đi được trong $10$ giây là $s_{10} = v_0(10) + \frac{1}{2}a(10)^2 = 4(10) + \frac{1}{2}(0.4)(100) = 40 + 20 = 60$ m.
Vậy đáp án là D.
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Sustainable Destinations
The new guide covers a range of sustainable travel options as well as sustainable hotels. All of them are (7) ________ and offer varying degrees of sustainable practices
Some suggested hotels:
Bettei Senjuan
Bettei Senjuan has a Green Key (8) ________ and is located at the foothills of Mount Tanigawa. A member of Relais & Châteaux luxury hotel group, the hotel has private open-air baths for each room, fed by flowing natural hot spring water.
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(Tham khảo bài văn của chủ đề trong đường link dưới đây ở trang 21)
https://tvsthpt.dlib.vn/app/doc-sach-ebook/d02db18272fe
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Đâu là ý đúng: Nguyên tắc thứ hai khi bón phân hóa học là gì?
Đặc điểm nổi bật trong xã hội hiện đại là?