Răspuns:
19,6 metri
Explicație:
G = m × g = 5 × 10 = 50 N
[tex]\displaystyle{ Ff = \frac{20}{100} \cdot 50 = 2 \cdot 5 = 10 \ N }[/tex]
[tex]\displaystyle{ E_{c} = \frac{m \cdot v^{2} }{2} }[/tex]
[tex]\displaystyle{ \frac{m \cdot v^{2} }{2} = 196 \rightarrow m \cdot v^{2} = 192 \cdot 2 = 392 }[/tex]
[tex]\displaystyle{ v^{2} = 392 : 5 = 78,4 }[/tex]
[tex]\displaystyle{ v = \sqrt{78,4} = 8,85 \ m/s }[/tex]
- Aplicam principiul al doilea fundamental al mecanicii.
-Ff = a × m
a = -Ff : m
a = -10 : 5
a = -2 m/s²
- Aplicam legea lui Galilei.
[tex]\displaystyle{ v_{1}^{2} = v_{0}^{2} + 2 \cdot a \cdot d }[/tex]
[tex]\displaystyle{ 0^{2} = \frac{392}{5} - 4d }[/tex]
[tex]\displaystyle{ 4d = \frac{392}{5}}[/tex]
d = 78,4 : 4
d = 19,6 m
