A certain radioactive substance decays to 40% of its original mass each year. If the initial mass is 500 grams, what will the mass be after 3 years?

Sun, 03 May 2026 22:18:53 +0000

**How Much Will Remain: The Quiet Math Behind Radioactive Decay in the US Context**
What happens to a 500-gram sample of a substance that loses 60% of its mass each year after just three years? Intriguing, isn’t it? This decay pattern—where a material retains only 40% of its previous mass annually—draws silent attention in science education, environmental reporting, and public discussions about long-term materials. As curiosity about radioactive substances grows alongside broader awareness of chemical stability and lifecycle tracking, understanding this decay becomes both practical and relevant. In the US, from energy studies to medical research and industrial safety, knowledge of such decay processes helps inform decisions—without sensationalism. **Why This Decay Pattern Is Gaining Traction**
The decay of 40% per year—meaning 60% loss—follows a predictable exponential formula, making it a reliable example of radioactive or chemical decay commonly referenced in science learning. Though not always labeled “radioactive” in casual discussion, many household and industrial materials exhibit similar behavior, reinforcing their presence in everyday discourse. With rising public interest in sustainable practices and long-term impacts, anecdotes and data around measurable decay processes are increasingly shared across digital platforms—especially in mobile-first Discover results, where concise, trustworthy insights perform best. **Understanding the Decay: A Clear Breakdown**
Starting with 500 grams, each year the mass is multiplied by 0.4 (40%). This consistent rate ensures precise, repeatable results:
After year 1: 500 × 0.4 = 200 grams
After year 2: 200 × 0.4 = 80 grams
After year 3: 80 × 0.4 = 32 grams
This arithmetic reflects exponential decay—meaning small annual losses accumulate toward significant total reduction over time, illustrating how even gradual processes shape long-term durability and safety planning. **Common Questions About the Decay Timeline**
Q: If 500 grams starts decaying at 40% per year, what remains after 3 years?
A: Mathematically, 500 × (0.4)^3 = 500 × 0.064 = 32 grams.
Q: Does this decay apply to all radioactive materials?
A: Not all decay rates follow this exact pattern; each isotope has a unique half-life and decay constant—this 40% rule is a simplified, consistent example used for clarity.
Q: How accurate are these projections over time?
A: The calculation is precise for short periods like 3 years but becomes theoretical beyond practical timelines, as real-world decay may involve multiple variables.