Bài 1:

a. \(s=vt=12.20.60=14400\left(m\right)\)

b. \(24\left(\dfrac{m}{s}\right)=86,4\left(\dfrac{km}{h}\right);6000\left(\dfrac{cm}{min}\right)=3,6\left(\dfrac{km}{h}\right)\)

\(\Rightarrow3,6< 54< 86,4< 108000\)

\(\Rightarrow6000\left(\dfrac{cm}{min}\right)< 54\left(\dfrac{km}{h}\right)< 24\left(\dfrac{m}{s}\right)< 108000\left(\dfrac{km}{h}\right)\)

Vậy.................

Bài 1:

a)Đổi:20 phút=1200 giây

Quãng đường người đó đi được:

     \(v=\dfrac{s}{t}\)⇒\(s=v.t=12.1200=14400\left(m\right)\)

b)(3)<(1)<(2)<(4)

\(8cm^2=0,0008m^2\)

\(\Rightarrow p=\dfrac{F}{S}=\dfrac{4.10}{0,0008.4}=12500\left(\dfrac{N}{m^2}\right)\)

a. \(v_{tb}=\dfrac{s'+s''}{t'+t''}=\dfrac{\left(2.60\right)+\left(3.50\right)}{2+3}=54\left(\dfrac{km}{h}\right)\)

b. \(m=2\left(tan\right)=2000\left(kg\right)\)

\(F_k=F_c=\dfrac{1}{10}.P=\dfrac{1}{10}.10.m=\dfrac{1}{10}.10.2000=2000\left(N\right)\)

đúng ko v ông

\(v=\dfrac{s}{t}=\dfrac{100}{2}=50\left(\dfrac{km}{h}\right)\simeq13,9\left(\dfrac{m}{s}\right)\)

a. \(s'=v't'=42\left(\dfrac{20}{60}\right)=14\left(km\right)\)

b. \(v_{tb}=\dfrac{s'+s''}{t'+t''}=\dfrac{14+12}{\left(\dfrac{20}{60}\right)+\left(\dfrac{15}{60}\right)}\simeq44,6\left(\dfrac{km}{h}\right)\)

\(t=\dfrac{s}{v}=\dfrac{2,25}{9}=0,25\left(h\right)\)

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