Đáp án:
\(\begin{array}{l}
9.C\\
p = p'\\
mv = (m + m')v' \Rightarrow v' = \dfrac{{mv}}{{m + m'}} = \dfrac{{m.v}}{{m + 2m}} = \dfrac{{m.9}}{{3m}} = 3m/s\\
10.A\\
{T_1} = {t_1} + 273 = 27 + 273 = 300^\circ K\\
{T_2} = {t_2} + 273 = - 13 + 273 = 260^\circ K\\
\dfrac{{{p_1}}}{{{T_1}}} = \dfrac{{{p_2}}}{{{T_2}}} \Rightarrow \dfrac{{{{6.10}^6}}}{{300}} = \dfrac{{{p_2}}}{{260}}\\
\Rightarrow {p_2} = 5,{2.10^6}Pa\\
11.D\\
W = {W_{d\max }} = \dfrac{1}{2}mv_{\max }^2 = \dfrac{1}{2}.m{.8^2} = 32m(J)\\
{{\rm{W}}_t} = {W_d} = \dfrac{W}{2} \Rightarrow mgh = \dfrac{{32m}}{2}\\
\Rightarrow 10.h = \frac{{32}}{2} \Rightarrow h = 1,6m\\
12.B\\
\Delta U = A + Q = 180 - 30 = 150J\\
13.A\\
\Delta U = A + Q \Rightarrow Q = \Delta U - A = 60 - 90 = - 30J\\
14.D\\
Q = mc\Delta t \Rightarrow c = \dfrac{Q}{{m\Delta t}} = \dfrac{{6900}}{{0,6.50}} = 230J/kg.K\\
15.C\\
\Delta U = A + Q \Rightarrow A = \Delta U - Q = 50 - 70 = - 20J\\
16.D\\
\Delta p = p' - p = - mv - mv = - 2mv = - 2.0,4.6 = - 4,8kg.m/s\\
17.C\\
A = Ph = mgh = 10.5,0,8 = 40J\\
18.A\\
P = 15kW = 15000W\\
A = Ph = mgh = 1000.10.30 = 300000J\\
P = \dfrac{A}{t} \Rightarrow t = \frac{A}{P} = \dfrac{{300000}}{{15000}} = 20s\\
19.A\\
A = Fs\cos 60 = 250.40.\cos 60 = 5000J\\
20.B\\
t = 2p30s = 150s\\
A = Ph = mgh = 10.10.6 = 600J\\
P = \dfrac{A}{t} = \dfrac{{600}}{{150}} = 4W
\end{array}\)
21.
a. Qúa trình đẳng nhiệt.
b. Quá trình đẳng áp.
c. Qúa trình đẳng nhiệt.
d. Qúa trình đẳng nhiệt.
