Nội dung mới nhất bởi muaphale

18/ \[\omega =\frac{2\pi }{T}=\frac{2\pi }{2}=\pi\] \[\Delta \varphi =\frac{2\pi .\Delta d}{\lambda }=\frac{2\pi .1,5}{6}=\frac{\pi }{2}\] \[Um=1,5cos( \pi t-\frac{\pi }{2}) (cm)\] 19/ \[\omega =\frac{2\pi }{T}=\frac{2\pi }{1,2}=\frac{5\pi }{3} (rad/s)\] \[v=\frac{s}{t}=\frac{15}{3}=5(m) suy ra...

13/ \[ frac{2\pi }{\lambda }=0,25 \] suy ra \[\lambda =\frac{2\pi }{0,25\pi } =8 (m) \] \[T=\frac{2\pi }{\omega }=\frac{2\pi }{2\pi }=1(s);v=\frac{\lambda }{T}=8(m/s) \] DA:A 14/(De bi loi o phan dap an) \[ Um=5cos(\omega t-\frac{2\pi \Delta d}{\lambda } =5cos(\omega...

9/ \[ k.\frac{\lambda }{2}=10 \] suy ra \[\lambda =\frac{20}{k} ; v=\lambda .f=\frac{20}{k}.20=\frac{400}{k}\] \[ 0,7\leq \frac{400}{k}\leq 1 \] lấy k=500 suy ra v=0,8(m/s) DA:B 10/ \[6\lambda =3 suy ra \lambda =0,5(cm);v=f.\lambda =400.0,5=50(cm/s)\] DA:B 11/De bi...

6 /\[ \frac{2\pi }{\lambda }=4 suy ra \lambda =\frac{2\pi }{4}=\frac{\pi }{2}\] \[f=\frac{\omega }{2\pi }=\frac{20}{2\pi }=\frac{10}{\pi }\] \[v=\lambda .f=\frac{\pi }{2}.\frac{10}{\pi }=5(m/s)\] DA: D 7/ \[k.\frac{\lambda }{2}=9 suy ra \lambda =\frac{18}{k}\] \[v=\lambda...

3/ \[v=\lambda .f=0,8.500=400(m/s)\] DA:D 4/ \[f=\frac{\omega }{2\pi }=\frac{4\pi }{2\pi }=2(hz)\\\lambda =\frac{v}{f}=\frac{1,2}{2}=0,6(m)\] DA:A 5/ \[u=8cos(10x-80t);\frac{2\pi }{\lambda }=10;\lambda =\frac{2\pi }{10}=\frac{\pi }{5}\\f=\frac{\omega }{2\pi }=\frac{80}{2\pi }=\frac{40}{\pi...

2/ \[f=\frac{v}{\lambda }=\frac{200}{4}=50(hz);T=\frac{\lambda }{v}=\frac{4}{200}=0.02(s)\] DA A

1/ \[T=\frac{t}{N-1}=\frac{18}{9}=2(s);v=\frac{\lambda }{T}=\frac{2}{2}=1(m/s)\]

\[\frac{\Delta T}{T}=\frac{\lambda \Delta t}{2}=5.10^{-5}\] \[\Theta =\frac{\left|\Delta T \right|}{T}t=5.10^{-5}.86400=4,32s\]

\[\frac{\Delta T}{T}=\frac{\lambda \Delta t}{2}=5.10^{-5}\]