The First Law and Why Perpetual Motion Fails

Lab Brief #7

🎯 Your mission

Understand the idea. Then look for it everywhere.

⚡ The twist

Nature loves to surprise the careful watcher.

What you'll learn

The first law of thermodynamics is conservation of energy applied to heat and work: the change in internal energy equals heat added minus work done by the system. No machine can output more energy than it takes in, which rules out perpetual motion of the first kind.

Key words

first law of thermodynamics
Change in internal energy equals heat supplied minus work done by the system.
perpetual motion machine
A hypothetical device that would produce energy from nothing; forbidden by the first law.

Make a hypothesis first

Before you start: write down what you think will happen, and why.

Say your guess out loud — then find out if you were right.

Step 1 of 4 · Read

Think about what you just learned: say what "first law of thermodynamics" and "perpetual motion machine" mean in your own words before you start.

Step 2 of 4 · Do

Research two historical perpetual-motion designs, sketch each, and write one paragraph per design identifying exactly which energy transfer its inventor failed to account for.

Step 3 of 4 · Observe

Record what actually happened, including anything that did not match what you expected.

Step 4 of 4 · Record

Write a conclusion that answers the question this lesson opened with, and state your uncertainty.

Question 1 of 2

The first law of thermodynamics is a statement of:

How sure are you?😐 maybe

Question 2 of 2

A machine claiming more energy out than in violates:

How sure are you?😐 maybe

Mind = blown

🔬 The more you look, the more nature shows you.

Nice work!

You got 0 of 2 right.

Next: Entropy and the Direction of Change All lessons

🎯

Next Smart Experiment

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✨ More to explore

🌍 Where you see this in real life: This shows up in your everyday life more than you'd think.

🏆 Stretch challenge (try it this week): Try one experiment in real life this week — even a tiny one.

👨‍👩‍👧 For the dinner table: “What's the most surprising thing you learned today?”

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