A Particle Physicist Observes Cosmic Rays Creating a New Particle $99.7 \%$

question 9

Multiple Choice

A particle physicist observes cosmic rays creating a new particle high in the atmosphere, and the speed of this particle is measured at $99.7 \%$ the speed of light. It is unstable, and is observed to decay in an average $37.0 \mu \mathrm { s }$ . If this particle were at rest in the laboratory, what would be its average lifetime?

• A) \(4.3 \mu \mathrm { s }\)
• B) \(12 \mu \mathrm { s }\)
• C) \(5.3 \mu \mathrm { s }\)
• D) \(2.9 \mu \mathrm { s }\)
• E) \(18 \mu \mathrm { s }\)

---

Definitions:

Exchange Rate

The price of one country's currency in terms of another currency, determining how much foreign currency can be obtained with a certain amount of domestic currency.

Quota

A quota is a government-imposed trade restriction that limits the number or monetary value of goods that can be imported or exported during a specific time period.

Foreign-Currency Exchange

The process of exchanging one country's currency for another's, often determined by market rates.

Budget Deficit

The situation in which a government's expenditures exceed its revenue, resulting in the need to borrow money or increase taxes.