Đáp án:
\(\begin{align}
& {{h}_{max}}=1,8m \\
& h=1,35m \\
& h=0,6m \\
\end{align}\)
Giải thích các bước giải:
\({{v}_{0}}=6m/s\)
a) Bảo toàn cơ năng ta có:
\(\begin{align}
& \text{W}={{\text{W}}_{dmax}}={{\text{W}}_{tmax}} \\
& \Leftrightarrow \dfrac{1}{2}.m.v_{0}^{2}=m.g.{{h}_{max}} \\
& \Rightarrow {{h}_{max}}=\dfrac{1}{2.10}{{.6}^{2}}=1,8m \\
\end{align}\)
b) Wt=3Wd
bảo toàn cơ năng:
\(\begin{align}
& \text{W}={{\text{W}}_{d}}\text{+}{{\text{W}}_{t}}=\dfrac{{{\text{W}}_{t}}}{3}+{{\text{W}}_{t}} \\
& \Leftrightarrow \dfrac{1}{2}.m.v_{0}^{2}=\frac{4}{3}m.g.h \\
& \Rightarrow h=\dfrac{3}{2.4.10}{{.6}^{2}}=1,35m \\
\end{align}\)
c) Wd=2Wt
\(\begin{align}
& \text{W}={{\text{W}}_{d}}\text{+}{{\text{W}}_{t}}=2{{\text{W}}_{t}}+{{\text{W}}_{t}} \\
& \Leftrightarrow \dfrac{1}{2}.m.v_{0}^{2}=3.m.g.h \\
& \Rightarrow h=\dfrac{1}{2.3.10}{{.6}^{2}}=0,6m \\
\end{align}\)
