Question

va rog ajutati-ma imi trebuie cat mai repede acest exercitiu

Answer 1

$v=72\frac{km}{h}$

a) Daca $\Delta t=10s\implies D=?$

$v=\frac{D}{\Delta t}\implies D=v\Delta t\\\text{Numeric, } D=10s\cdot 72\frac{km}{h}\\D=10s\cdot 72\frac{1000m}{3600s}=10s\cdot 20\frac{m}{s}=200m$

b) Daca $D=25km\implies\Delta t=?$

$v=\frac{D}{\Delta t}\implies \Delta t=\frac{D}{v}\\\text{Numeric, }\Delta t=\frac{25km}{72\frac{km}{h}}=\frac{25000m}{20\frac{m}{s}}=1250s\approx 20,8333min$

Answer 2

$v = \frac{d}{t} \\ \\ 72 \: km/h = 72000 \: m \div 3600 \: s = 20 \: m/s \\ \\ 1) \\ \\ d = v \times t = 20 \: m/s \times 10 \: s = 200 \: m \\ \\ 2) \\ \\ t = \frac{d}{v} = 25000 \div 20 = 1250 \: s = 1250 \div 60 = 20,8 \: minute$