Bullet Block Explained!

TL;DR

Despite expectations, wood blocks shot straight through the center of mass and slightly off to one side go to the exact same height.

Transcript

In my last video we performed an experiment in which two identical wood blocks were shot with the same rifle, one through the center of mass and the other one slightly off to one side. Now if you haven’t seen that video yet, then click here now and go and watch it. Or, if you are on a mobile device, click the link in the description. So the questio... Read More

Key Insights

• 👯 Even experienced and intelligent people can make incorrect predictions in counterintuitive experiments.
• 🚫 The conservation of momentum explains why both blocks go to the same height.
• 👱 Rotational energy and air resistance are not significant factors in determining the height difference.

Questions & Answers

Q: Why did people expect the block shot off to one side to go lower?

People expected this because the spinning block appeared to have more energy, but rotational energy doesn't affect the height of the block.

Q: Did the experiment results differ when repeated multiple times?

Yes, when the experiment was repeated multiple times, it was found that the blocks did not all go to the same height. However, the spinning blocks did not go systematically lower than the non-spinning blocks.

Q: Could air resistance explain the results?

Air resistance was suggested as a factor, but the difference in air resistance between the spinning and non-spinning blocks was negligible.

Q: Why does the spinning block end up with more rotational energy?

When the bullet strikes the wood, a lot of kinetic energy is lost. The spinning block may have less loss of energy, allowing it to rotate and go to the same height as the non-spinning block.

Summary & Key Takeaways

• In an experiment, wood blocks shot with a rifle through the center of mass and slightly off to one side were found to go to the same height.

• Many people incorrectly predicted that the block shot off to one side would go lower, while only 21% predicted that both blocks would go to the same height.

• Video responses were received, with some suggesting rotational energy and air resistance as factors, but the ultimate answer lies in the conservation of momentum.