Math Problem Statement
Solution
This problem involves understanding angular momentum and rotational inertia. Let's analyze it step by step:
Given
- A circular dartboard spins with constant angular speed.
- The first dart lands at the bullseye (center).
- The second dart lands at the outer edge of the dartboard.
We need to determine what happens after each dart hits.
Assumptions
- The darts stick to the dartboard upon impact.
- The dartboard is initially spinning in a vacuum (no air resistance or friction).
- The mass of the dart is non-negligible compared to the dartboard.
- Conservation of angular momentum applies because there is no external torque.
Analysis
After the first dart hits:
- The dart lands at the bullseye (center), contributing no torque because the lever arm (distance from the axis of rotation) is zero.
- The rotational inertia of the system (dartboard + dart) does not change significantly.
- Outcome: The angular speed of the dartboard remains constant after the first dart hits.
After the second dart hits:
- The second dart lands at the outer edge of the dartboard, increasing the system's rotational inertia. The formula for rotational inertia is , where is the distance from the axis of rotation (outer edge here).
- Angular momentum () must be conserved. As increases due to the second dart, the angular speed () decreases.
- Outcome: The angular speed of the dartboard decreases after the second dart hits.
Conclusion
- After the first dart hits: The angular speed of the dartboard remains unchanged.
- After the second dart hits: The angular speed of the dartboard decreases due to the increase in rotational inertia.
Let me know if you'd like further clarification or additional details!
Related Questions:
- What would happen if the dartboard had friction at the bearing?
- How does the mass of the dartboard influence the effect of the second dart?
- How would angular speed change if multiple darts hit at different radii?
- What is the relationship between torque and angular momentum in such systems?
- How can conservation of energy be used to analyze this problem?
Tip:
Always check whether external forces or torques act on a system when applying conservation laws.
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Math Problem Analysis
Mathematical Concepts
Angular Momentum
Rotational Inertia
Conservation of Angular Momentum
Formulas
L = I * ω (Angular Momentum)
I = I_board + m * r^2 (Rotational Inertia)
Theorems
Conservation of Angular Momentum
Suitable Grade Level
Grades 11-12 or introductory college-level physics
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