A physicist is measuring the decay of a radioactive substance. The half-life of the substance is 5 years. If the initial mass is 200 grams, what is the mass remaining after 15 years?

Wed, 06 May 2026 02:12:49 +0000

**Discover Why Radioactive Decay Matters—Even in Everyday Life**
When scientists study how matter transforms over decades, understanding radioactive decay remains foundational. A physicist measuring the decay of a radioactive substance with a 5-year half-life offers more than just a math problem—it reflects a real-world process central to medicine, energy, and scientific research. With growing public interest in health, sustainability, and advanced technologies, basic principles of decay are surfacing across US digital platforms. This blend of curiosity, precision, and relevance makes this topic timely and impactful for learners seeking clear, trustworthy insight. **Why This Topic Is Trending Now in the US**
Recent shifts in public awareness around nuclear science stem from increased focus on safe energy practices, medical imaging advancements, and environmental monitoring. Radioactive decay principles underpin cancer treatments like radiation therapy and digital imaging techniques such as PET scans. Moreover, discussions about long-term storage of industrial radioactive materials remain relevant in policy and environmental debates. Educators and science communicators note rising engagement with radioactive processes—particularly among mobile users—hungry for accessible yet rigorous explanations. This growing interest creates a strong chance for content that answers a clear, specific question with factual precision. **How Radioactive Decay Follows a Predictable Pattern**
Radioactive decay is a naturally occurring process where unstable atoms gradually transform into other elements over time. With a half-life of 5 years, a substance loses half its mass every five years. Starting with 200 grams, after the first half-life (5 years), 100 grams remain. After the second (10 years), 50 grams remain. After the third (15 years), only 25 grams remain. This consistent pattern follows exponential decay, measurable through radiation detection and radiation monitoring tools used in multiple fields. Understanding this principle helps clarify why precise timing and measurement matter in both research and practical applications. **Common Questions and Clear Answers**
**H3: How is half-life defined, and why does it matter?**
Half-life is the time needed for half of a radioactive substance’s mass to decay. In this 15-year case, 15 ÷ 5 = 3 half-lives. The substance undergoes exponential reduction: 200g → 100g → 50g → 25g. This predictable drop matters in safety assessments, environmental impact studies