Question

A wooden rod of negligible mass and length 79.0 cm is pivoted about a horizontal axis through its center. A white rat with mass 0.510 kg clings to one end of the stick, and a mouse with mass 0.210 kg clings to the other end. The system is released from rest with the rod horizontal.

Answer 1

Answer:

$v=1.307m/s$

Explanation:

The velocity of both animals are the same the analysis of the motion is:

$E_{pr}-E_{pw}=K_{Ew}+K_{Er}$

$E_{pw}=m*g*h$, $h=0.395 cm$

$E_{pw}=0.510kg*9.8m/s^2*0.395m=197.421x10^{-3}J$

$E_{pr}=m*g*h$, $h=0.395 cm$

$E_{pr}=0.210kg*9.8m/s^2*0.395m=812.91x10^{-3}J$

Replacing in the initial equation now solve to velocity in this case is the same for both animals so:

$615.489x10^{-3}J=\frac{1}{2}*v^2[0.51+0.21]kg$

$v^2=\frac{1.2309J}{0.72kg}=1.709m^2/s^2$

$v=1.307m/s$