Đáp án:

 a,$1184\left( {N/m} \right)$

b. ${W_t} = 0,059\left( J \right)$

${W_d} =  0,474\left( J \right)$

c .$90\left( {cm/s} \right)$

Giải thích các bước giải:

$\begin{array}{l}
a.f = \frac{1}{{2\pi }}\sqrt {\frac{k}{m}}  \Rightarrow k = m.{\left( {2\pi f} \right)^2} = 0,3.{\left( {2\pi .10} \right)^2} = 1184\left( {N/m} \right)\\
b.{W_t} = \frac{1}{2}.m{\left( {2\pi f} \right)^2}.{x^2} = \frac{1}{2}.0,3.{\left( {2\pi .10} \right)^2}.0,{01^2} = 0,059\left( J \right)\\
{W_d} = \frac{1}{2}.m{\left( {2\pi f} \right)^2}.({A^2} - {x^2}) = \frac{1}{2}.0,3.{\left( {2\pi .10} \right)^2}.(0,{03^2} - 0,{01^2}) = 0,474\left( J \right)\\
c.s = 1,5cm\\
\varphi  = \frac{\pi }{3} \Rightarrow t = T.\frac{\varphi }{{2\pi }} = \frac{\varphi }{{2\pi f}} = \frac{1}{{60}}\left( s \right)\\
{v_{tb}} = \frac{s}{t} = 90\left( {cm/s} \right)
\end{array}$