Ballistic Cylinder: Angular Velocity After Bullet Impact

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SUMMARY

The discussion focuses on calculating the angular velocity of a solid cylinder after being impacted by a bullet. A 13.0 g bullet traveling at 578.1 m/s strikes a 24.1 kg cylinder with a radius of 0.11 m, initially at rest. The conservation of angular momentum is applied to find the angular velocity, with the correct calculation yielding approximately 1.13 rad/s. Participants noted the importance of considering only the tangential component of the bullet's impulse for accurate results.

PREREQUISITES
  • Understanding of conservation of angular momentum
  • Familiarity with rotational dynamics
  • Basic knowledge of impulse and momentum
  • Ability to perform calculations involving mass, velocity, and radius
NEXT STEPS
  • Review the principles of conservation of angular momentum in collision scenarios
  • Study the effects of impulsive forces on rigid bodies
  • Learn about the moment of inertia for different shapes, particularly cylinders
  • Explore advanced rotational dynamics problems involving multiple bodies
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This discussion is beneficial for physics students, educators, and anyone interested in mechanics, particularly those studying rotational motion and collision dynamics.

lew44
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Homework Statement



A 13.0 g bullet is fired at 578.1 m/s into a solid cylinder of mass 24.1 kg and a radius 0.11 m. The cylinder is initially at rest and is mounted on fixed vertical axis that runs through it's center of mass.
The line of motion of the bullet is perpendicular to the axle and at a distance 2.20 cm from the center. Find the angular velocity of the system after the bullet strikes and adheres to the surface of the cylinder.

Homework Equations



conservation of angular momentum

The Attempt at a Solution



I tried,

.013 x (.022^2) (578.1/.11) = ((.013)(.022^2) + (.5)(24.1)(.11^2)) x W

I got .227rad/s as an answer but that was incorrect. Any ideas?
 
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If you think of the bullet as an impulsive force on the cylinder you should be able to figure out how much of that force is radial to the cylinder (which is absorbed by the bearing) and how much is tangential (which will make the cylinder rotate). If I do the calculation I end up with a angular speed of around 1.13 rad/s.

The right-hand side of your equation looks ok to me, but I'm not sure I understand how you arrived at the left-hand side of your equation. I get something similar but not quite the same. Perhaps you missed taking only the tangential part of the impulse.
 

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