Rotational Collision of Sliding Boys: Velocity and Kinetic Energy Analysis

AI Thread Summary
Two boys, Jacob and Ethan, are sliding towards each other on a frictionless surface before colliding and locking arms. The initial velocities are 8 m/s for Jacob and 11 m/s for Ethan, leading to a calculated post-collision velocity of 9.34 m/s and a mechanical energy fraction of 1.66 x 10^(-4) remaining after the collision. When they repeat the collision along parallel lines and rotate about their center of mass, the center of mass velocity and angular velocity need to be determined. The moment of inertia for the system is crucial for calculating the angular velocity, and clarification on the inelastic collision calculations is sought. The discussion emphasizes the need for accurate calculations in both linear and rotational dynamics.
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Two boys are sliding towards each other on a frictionless, ice-covered parking lot. Jacob, mass 45kg, is sliding towards the right at 8m/s and Ethan, mass 31kg, is sliding towards the left at 11m/s along the same line. When they meet, they grab each other and hang on.
(a) What is their velocity immediately after?
(b) What fraction of their initial KE is still mechanical energy after their collision?

That was so much fun that the boys decided to repeat the collision with the same original velocities this time along parallel lines 1.20m apart. At the closest approach they lock arms and start rotating about their common center of mass. Model the boys as particles and their arms as a cord that does not stretch.
(c) Find the velocity of their center of mass.
(d) Find the angular velocity.
(e)What fraction of their initial KE is still mechanical energy after they link arms?My answers to part (a) and (b) are 9.34m/s and 1.66 x 10^(-4) respectively.
For the second part of the question, I need the moment of inertia of the system of boys. How can I find it? Any help?
 
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hey are your answers in (a) and (b) correct? it's perfectly inelastic collision right?
shouldn't it be 45x8 + 31x(-11) =(45+31)(Y), where Y is +0.25?
 
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