Răspuns:
a) [tex]E_c[/tex] = 600 kJ
b) [tex]F_f[/tex] = 200 N
Rezolvare:
Scriem datele problemei:
m = 3 t = 3000 kg
v = 72 km/h = 20 m/s
P = 40 kW = 40000 W
__________________
a) [tex]E_c=?[/tex]
b) [tex]F_f=?[/tex]
a) Pentru a afla energia cinetică a camionului folosim formula:
[tex]\bf\red{\boxed{E_c=\frac{mv^2}{2}}}\\[/tex]
- [tex]E_c[/tex] = energia cinetică
- m = masa
- v = viteza
[tex]E_c=\frac{3000\times20^2}{2}=\frac{3000\times400}{2}=3000\times200=\bf600000\:J=600\:kJ\\[/tex]
b) [tex]P=\frac{Fd}{t}=Fv\\[/tex]
[tex]\implies F_f=\frac{P}{v}=\frac{40000}{20}=\bf\boxed{2000\:N}\\[/tex]
Succes! ❀
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