Question

Rapid daca puteti, multumesc!

Answer 1

Răspuns:

vB=40√2 m/s;   vC=20√5 m/s

Explicație:

Energia este conservată deci:

$E_{pi}=E_{cf}\ \Rightarrow E_{c}+E_{p} =0.4kg*10\frac{N}{kg}*5m=20J \\ \Rightarrow m(gh+\frac{1}{2}v^{2})=20J \Rightarrow gh+\frac{1}{2}v^{2}=\frac{200J}{4kg} \Rightarrow v=\sqrt{2*50*10*h} \frac{m}{s}\\ v=10\sqrt{10h} \frac{m}{s} \Rightarrow v_{B}= 10\sqrt{32}\frac{m}{s}=40\sqrt{2}\frac{m}{s}; v_{C}= 10\sqrt{20}\frac{m}{s}=20\sqrt{5}\frac{m}{s};$