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Câu hỏi: Cơ năng của một vật có khối lượng m dao động điều hòa với chu kì $\text{T}$ và biên độ $\text{A}$ được tính theo biểu thức
A. $\text{W}=\dfrac{\text{4}{{\!\!\pi\!\!}^{\text{2}}}\text{m}{{\text{A}}^{\text{2}}}}{{{\text{T}}^{\text{2}}}}.$
B. $\text{W}=\dfrac{{{\!\!\pi\!\!}^{\text{2}}}\text{m}{{\text{A}}^{\text{2}}}}{\text{2}{{\text{T}}^{\text{2}}}}.$
C. $\text{W}=\dfrac{{{\!\!\pi\!\!}^{\text{2}}}\text{m}{{\text{A}}^{\text{2}}}}{\text{4}{{\text{T}}^{\text{2}}}}.$
D. $\text{W}=\dfrac{\text{2}{{\!\!\pi\!\!}^{\text{2}}}\text{m}{{\text{A}}^{\text{2}}}}{{{\text{T}}^{\text{2}}}}.$
A. $\text{W}=\dfrac{\text{4}{{\!\!\pi\!\!}^{\text{2}}}\text{m}{{\text{A}}^{\text{2}}}}{{{\text{T}}^{\text{2}}}}.$
B. $\text{W}=\dfrac{{{\!\!\pi\!\!}^{\text{2}}}\text{m}{{\text{A}}^{\text{2}}}}{\text{2}{{\text{T}}^{\text{2}}}}.$
C. $\text{W}=\dfrac{{{\!\!\pi\!\!}^{\text{2}}}\text{m}{{\text{A}}^{\text{2}}}}{\text{4}{{\text{T}}^{\text{2}}}}.$
D. $\text{W}=\dfrac{\text{2}{{\!\!\pi\!\!}^{\text{2}}}\text{m}{{\text{A}}^{\text{2}}}}{{{\text{T}}^{\text{2}}}}.$
Cơ năng của vật $\text{W}=\dfrac{1}{2}\text{m}{{\!\!\omega\!\!}^{\text{2}}}{{\text{A}}^{\text{2}}}=\dfrac{1}{2}\text{m}{{\left( \dfrac{\text{2 }\!\!\pi\!\!}{\text{T}} \right)}^{2}}{{\text{A}}^{2}}=\text{m}\dfrac{\text{2}{{\!\!\pi\!\!}^{\text{2}}}}{{{\text{T}}^{\text{2}}}}{{\text{A}}^{2}}$Đáp án D.