Conservation of Angular Momentum: a Metal Bar Is Hanging from a Hook

question 33

Multiple Choice

Conservation of angular momentum: A metal bar is hanging from a hook in the ceiling when it is suddenly struck by a ball that is moving horizontally (see figure) . The ball is covered with glue, so it sticks to the bar. During this collision

• A) the angular momentum of the system (ball and bar) is conserved about the hook because only gravity is acting on the system.
• B) the angular momentum of the system (ball and bar) is not conserved because the hook exerts a force on the bar.
• C) the angular momentum of the system (ball and bar) is conserved about the hook because neither the hook nor gravity exerts any torque on this system about the hook.
• D) both the angular momentum of the system (ball and bar) and its kinetic energy are conserved.
• E) both the linear momentum and the angular momentum of the system (ball and bar) are conserved.

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Definitions:

Expected Rate of Return

The anticipated amount of profit or loss an investment is projected to generate over a specific period, expressed as a percentage.

Portfolio of Risky Securities

A collection of investments that contain a degree of risk, with the expectation of achieving higher returns compared to risk-free assets.

Weighted Sum

A mathematical technique where each component is multiplied by a factor reflecting its importance before their sum is computed.

Variance of Returns

A measure of the dispersion of returns for a given security or market index, typically used to gauge the risk associated with a particular investment.