Question

Care este raportul energiilor cinetice ale doua corpuri daca unul are masa de 630g si viteza de 10m/s iar altul are masa de 40g si viteza 15m/s??

Answer 1

m1=630g

m2=40g

v1=10m/s

v2=15m/s

Ec1/Ec2=?

Rezolvare:

Ec1=m1×v1^2/2=0,630Kg×100/2=31,5J

Ec2=m2×v2^2/2=0,04Kg×225/2=4,5

Answer 2

$\displaystyle m_1=630~g;~v_1=10~\frac{m}{s};~m_2=40~g;~v_2=15~\frac{m}{s}\\ \\m_1=630~g=0,63~kg\\ \\m_2=40~g=0,04~kg\\ \\E_{c_1}=\frac{m_1v_1^ 2}{2} \Rightarrow E_{c_1}=\frac{0,63\cdot 10^2}{2} \Rightarrow E_{c_1}=\frac{0,63 \cdot 100}{2}\Rightarrow E_{c_1}=\frac{63}{2}\Rightarrow \\ \\ \Rightarrow E_{c_1}=31,5~J\\ \\E_{c_2}=\frac{m_2v_2^ 2}{2} \Rightarrow E_{c_2}=\frac{0,04 \cdot 15^2}{2}\Rightarrow E_{c_2}=\frac{0,04\cdot225}{2} \Rightarrow E_{c_2}=\frac{9}{2} \Rightarrow \\ \\ \Rightarrow E_{c_2}=4,5~J$

$\displaystyle\frac{E_{c_1}}{E_{c_2}}=\frac{31,5}{4,5}= \mathbf{7}$