Respuesta :
72 ergs
Explanation
Step 1
Kinetic energy varies jointly as the mass and the square of the velocity,then
[tex]E_k=\lambda\cdot m\cdot v^2[/tex]where
m is the mass, v is the velocity and
[tex]\lambda\text{ is a constant}[/tex]A mass of 8 grams and velocity of 3 centimeters per second has a kinetic energy of 36 ergs
[tex]\begin{gathered} E_k=\lambda m\cdot v^2 \\ 36\text{ erg=}\lambda\cdot8\cdot3^2 \\ 36=\lambda\cdot8\cdot9 \\ 36=\lambda\cdot72 \\ \text{divide both sides by 72} \\ \frac{36}{72}=\lambda \\ \lambda=\frac{1}{2} \end{gathered}[/tex]so, the equation is
[tex]\begin{gathered} E_k=\lambda\cdot m\cdot v^2 \\ E_k=\frac{1}{2}\cdot m\cdot v^2 \end{gathered}[/tex]Step 2
now , we know the equation to find the kinetic energy of a object if we know its mass and its velocity
Let
mass= 4 grams
velocity = 6 cms per sec
then
[tex]\begin{gathered} E_k=\frac{1}{2}\cdot m\cdot v^2 \\ E_k=\frac{1}{2}\cdot4gr\cdot(6\frac{\operatorname{cm}}{\sec})^2 \\ E_k=\frac{1}{2}\cdot4gr\cdot36\frac{\operatorname{cm}}{\sec ^2} \\ E_k=72\text{ erg} \end{gathered}[/tex]I hope this helps you
