Đáp án:
\(\begin{array}{l}
{\rm{a}}.250\left( J \right)\\
b.{h_{max}} = 5\left( m \right)\\
c.1,25\left( m \right)\\
d.{v_D} = 4,33\left( {m/s} \right)
\end{array}\)
Giải thích các bước giải:
\(\begin{array}{l}
{\rm{a}}{\rm{.}}{{\rm{W}}_A} = \frac{1}{2}mv_0^2 = \frac{1}{2}{.5.10^2} = 250\left( J \right)\\
b.{{\rm{W}}_B} = {{\rm{W}}_A}\\
\Rightarrow mg{h_{max}} = 250\\
\Rightarrow 5.10.{h_{max}} = 250\\
\Rightarrow {h_{max}} = 5\left( m \right)\\
c.{{\rm{W}}_{dC}} = 3{W_{tC}}\\
\Rightarrow {W_{tC}} = \frac{{{{\rm{W}}_A}}}{4}\\
\Rightarrow {h_C} = \frac{1}{4}{h_{max}} = \frac{1}{4}.5 = 1,25\left( m \right)\\
d.{{\rm{W}}_{{\rm{dD}}}} = 3{W_{tD}}\\
\Rightarrow {{\rm{W}}_{{\rm{dD}}}} = \frac{3}{4}{{\rm{W}}_A}\\
\Rightarrow \frac{1}{2}mv_D^2 = \frac{3}{4}.250\\
\Rightarrow \frac{1}{2}.5.v_D^2 = \frac{3}{4}.250\\
\Rightarrow {v_D} = 4,33\left( {m/s} \right)
\end{array}\)
