\(R_{tđ}=\dfrac{R_1\cdot R_2}{R_1+R_2}=\dfrac{24\cdot12}{24+12}=8\Omega\)

\(I=\dfrac{U}{R}=\dfrac{12}{8}=1,5A\)

\(P=\dfrac{U^2}{R}=\dfrac{12^2}{8}=18W\)

\(Q_{tỏa1}=A_1=U_1\cdot I_1\cdot t=12\cdot\dfrac{12}{24}\cdot1\cdot3600=21600J\)

\(Q_{tỏa2}=A_2=U_2\cdot I_2\cdot t=12\cdot\dfrac{12}{12}\cdot1\cdot3600=43200J\)

Bài 3.

Định luật ll Niu-tơn:

\(\overrightarrow{F}+\overrightarrow{F_{ms}}=m\cdot\overrightarrow{a}\)

\(\Rightarrow F-F_{ms}=m\cdot a\)

Gia tốc vật:

\(a=\dfrac{F-F_{ms}}{m}=\dfrac{4,5-\mu mg}{m}=\dfrac{4,5-0,2\cdot1,5\cdot10}{1,5}=1\)m/s²

Vận tốc vật sau 2s:

\(v=a\cdot t=1\cdot2=2\)m/s

Gì dài z má =))

ai nhanh ,đúng,mk k 3k

e, bạn là ai sao lại kbạn with me

a, \(I_1=I_3=2I_2\)

\(I_2=\dfrac{7,8}{12}=0,65\left(A\right)\) \(\Rightarrow I_3=I_1=1,3\left(A\right)\)

\(\Rightarrow U_3=7,8-U_1=7,8-1,3.4=2,6\left(V\right)\)

\(\Rightarrow R_3=\dfrac{2,6}{1,3}=2\left(\Omega\right)\)

b, k đóng ta có mạch (R1//R2)nt(R3//R4)

\(\Rightarrow R_{tđ}=\dfrac{4.6}{10}+\dfrac{2.6}{8}=3,9\left(\Omega\right)\)

\(\Rightarrow I_k=\dfrac{7,8}{3,9}=2\left(A\right)\)

\(\Rightarrow U_{12}=\dfrac{4.6}{10}=2,4\left(V\right)\)

\(\Rightarrow U_{34}=2.1,5=3\left(V\right)\)

\(\Rightarrow I_1=\dfrac{2,4}{4}=0,6\left(A\right);I_2=\dfrac{2,4}{6}=0,4\left(A\right)\)

\(\Rightarrow I_3=\dfrac{3}{2}=1,5\left(A\right);I_4=\dfrac{3}{6}=0,5\left(A\right)\)

D- C - B - A - C - C - B - C - B - B - A -B 
F - T- F -F