College Board-Aligned Original Notes

AP Physics 2: Algebra-Based Unit 15 Topic 2: Energy in modern physics (energy in radioactive decay and E = mc 2 )

Connect Energy in modern physics (energy in radioactive decay and E = mc 2 ) to a model, the evidence that supports it, and the variables that change the system.

Unit 15: Modern Physics. College Board exam weighting listed for this unit: 12%-15% of exam score.

What to Know

Identify the system, surroundings, and scale before explaining a process.
Use diagrams, graphs, and tables as evidence rather than decoration.
For quantitative questions, keep units visible from the setup through the final answer.
Always connect this topic back to the larger unit: Modern Physics.

Detailed Notes

Energy in modern physics (energy in radioactive decay and E = mc 2 ) belongs to Modern Physics, so study it as part of a larger scientific system rather than as a stand-alone fact. Start by identifying what is being described, what is changing, and what evidence would let you defend a claim.

In AP Physics 2: Algebra-Based, strong answers usually connect a visible pattern to an underlying mechanism. That means explaining not only what happens, but why it happens at the particle, organism, environmental, or system level.

For AP-style questions, expect this topic to appear with graphs, diagrams, data tables, experiments, or written scenarios. Your job is to describe the evidence, apply the correct concept, and explain the reasoning that connects them.

Key Vocabulary

Work

Energy transferred when a force acts through a displacement.

Kinetic energy

Energy of motion.

Momentum

Product of mass and velocity.

Impulse

Change in momentum caused by a force acting over time.

Torque

A rotational effect of a force.

Quick Practice

How would you explain Energy in modern physics (energy in radioactive decay and E = mc 2 ) in one or two AP-style sentences?

Name the concept, apply it to a specific example or source, and explain the reasoning that connects the evidence to your answer.