giup minh lam bai mo dau ve song co nay nhe

P

phinzin

giải

T=1/f = 0.1s.
[TEX]\lambda = \frac v f = \frac{0.4}{10} = 0.04 m \\ \\ 30cm = 0.3 m= 7.5 \lambda \\ \\ 1T \text{ song truyen duoc } 1 \lambda \Rightarrow 7.5 \lambda \Leftrightarrow 7.5T \\ \\ \Rightarrow s= 7.5 * 4*A = 60cm [/TEX]
 
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