Câu 3.
Áp suất các chân ghế lên sàn:
\(p=\dfrac{F}{S}=\dfrac{4\cdot10}{4\cdot5\cdot10^{-4}}=20000Pa\)
Câu 3:
\(5cm^2=0,0005m^2\)
\(\Rightarrow p=\dfrac{F}{S}=\dfrac{4\cdot10}{0,0005\cdot4}=20000\left(\dfrac{N}{m^2}\right)\)
Câu 4:
\(3\left(\dfrac{m}{s}\right)=10,8\left(\dfrac{km}{h}\right)\)
\(v_{tb}=\dfrac{s'+s''}{t'+t''}=\dfrac{3+2}{0,5+\left(2:10,8\right)}\approx7,3\left(\dfrac{km}{h}\right)\)
Câu 4.
Thời gian đi quãng đường 2:
\(t_2=\dfrac{S_2}{v_2}=\dfrac{2}{3\cdot3,6}=\dfrac{5}{27}h\)
Vận tốc trung bình:
\(v_{tb}=\dfrac{S_1+S_2}{t_1+t_2}=\dfrac{3+2}{0,5+\dfrac{5}{27}}=7,3\)km/h
