Đáp án:
\(\begin{array}{l}
8.\\
{A_P} = 144J\\
{P_{tb}} = 120W\\
{P_{tt}} = 240W\\
9.\\
a.\\
F = 52500N\\
b.\\
P = 26250t\\
c.\\
A = 2362500J
\end{array}\)
Giải thích các bước giải:
\(\begin{array}{l}
8.\\
s = \frac{1}{2}g{t^2} = \frac{1}{2}.10.1,{2^2} = 7,2m\\
{A_P} = Ps = 2.10.7,2 = 144J\\
{P_{tb}} = \frac{A}{t} = \frac{{144}}{{1,2}} = 120W\\
v = gt = 10.1,2 = 12m/s\\
{P_{tt}} = Pv = 2.10.12 = 240W\\
9.\\
a.\\
F - P = ma\\
F = P + ma = 5000.10 + 5000.0,5 = 52500N\\
b.\\
P = \frac{A}{t} = \frac{{Fs}}{t} = Fv = Fat = 52500.0,5t = 26250t\\
c.\\
s = \frac{1}{2}g{t^2} = \frac{1}{2}{.10.3^2} = 45m\\
A = Fs = 52500.45 = 2362500J
\end{array}\)
