A bullet of mass m and speed v passes completely through a pendulum bob of mass M. The bullet emerges with a speed of v/2. The pendulum bob is suspended by a stiff rod of length script l and negligible mass. What is the minimum value of v such that the pendulum bob will barely swing through a complete vertical circle? (Use any variable or symbol stated above along with the following as necessary: g. Be sure to use script l from physPad.)
v =

Respuesta :

Answer:

[tex]v = \sqrt{16\cdot g \cdot L}[/tex]

Explanation:

The physical phenomenon is described by the Principles of Momentum Conservation and Energy Conservation:

Momentum

[tex]m \cdot v = M\cdot \frac{v}{2} + m \cdot v'[/tex]

Energy

[tex]\frac{1}{2}\cdot m \cdot v^{2} = \frac{1}{8}\cdot M \cdot v^{2} + \frac{1}{2}\cdot m \cdot v'^{2}[/tex]

[tex]\frac{1}{8}\cdot M\cdot v^{2} = 2\cdot M\cdot g \cdot L[/tex]

The minimum speed of the pendulum bob so that it could barely swing through a complete vertical cycle is:

[tex]\frac{1}{8}\cdot v^{2} = 2\cdot g\cdot L[/tex]

[tex]v^{2} = 16\cdot g\cdot L[/tex]

[tex]v = \sqrt{16\cdot g \cdot L}[/tex]