【Quiz】Which Is Heavier After the Cut? A Carrot at the Balance Point! – Exploring Torque with Vegetables
I’m Ken Kuwako, your Science Trainer. Every day is an experiment!
Sometimes, our intuition gets “tricked” by the laws of physics. For instance, imagine a single carrot perfectly balanced on a string. If you were to cut that carrot right at the balancing point, wouldn’t you think both sides would weigh the same? Surprisingly, this simple scenario hides a secret of physics that supports our daily lives. Today, I’ve got a “Physics Quiz” that might make your brain itch a little. Let’s think through it together!
Quick Quiz Time! Ta-da!
Suppose we hang a carrot by a string like this. (Try to visualize the diagram!)
In this setup, we tied the string slightly to the right of the center, on the thicker side, to keep it perfectly horizontal. Now, here is the challenge: If we were to slice the carrot in two exactly where the string is, which part would be heavier: the left side (the thin end) or the right side (the thick end)?
Take a moment to think about it. Got an answer? Let’s reveal the truth! I’ll explain the answer in this video.
A Surprising Result! The weights were actually different?
Believe it or not, they aren’t equal! One side is clearly heavier. “Wait, which one?” you might ask. This is a classic masterpiece in the world of physics puzzles. Let’s break down why the weights differ. The keyword here is Moment of Force (or Torque).
For the thick side:
68g
And for the thin side: 
56g
That’s right—the thick side is heavier!
The thick side is heavier, while the thin side is lighter.
Why does this happen? Let’s use a bit of mathematical logic to solve this mystery.
What is the “Turning Force”? Understanding Moments
Imagine trying to loosen a rusty bolt with a wrench. If you want to apply the strongest force possible, where do you grab the wrench? Instinctively, you probably grab the very end of the handle. This is because the further you are from the center (the axis of rotation), the more “turning power” you generate with less effort. This concept is called a Moment. Mathematically, it looks like this:
M = F × L
Moment = Force × Arm Length
This formula is vital! It’s not just about the “weight (force)”; the “distance from the center (arm length)” is what ultimately determines the rotational strength.
When Moments Balance Out
Let’s make a simple mobile using a light rod and two identical weights. In this case, if you tie the string exactly in the middle of the rod, it stays perfectly level.
If we calculate the moments around the string (the axis), they are equal on both sides:
Left side: 2N × 10cm = 20N·cm (Counter-clockwise)
Right side: 2N × 10cm = 20N·cm (Clockwise)
When the clockwise and counter-clockwise moments are equal, the object stops rotating and stays still. We call this “Moment Equilibrium.”
What happens when we hang different weights?
Now, let’s get to the heart of the matter. Let’s hang two different weights: a heavy 6N ball and a light 2N ball. To make them balance, you can’t tie the string in the middle; you have to shift it closer to the heavier side.
In practice, they will balance at a point like this:
Left side: 6N × 5cm = 30N·cm
Right side: 2N × 15cm = 30N·cm
The math checks out—the moments are identical! But if we were to snip the rod right at the string…
Naturally, the left piece (carrying the 6N weight) is much heavier than the right piece (carrying the 2N weight).
The Carrot Mystery Solved!
Now, let’s go back to our original carrot.
The string was tied much closer to the thick end than the thin end. This is exactly the same situation as our “6N vs 2N” experiment.
Because the thin, long part is far from the center (the string), even a small weight can generate a large moment (turning force). Conversely, because the thick part is so close to the center, it has to be significantly heavier to maintain the balance. Therefore, the answer is: The thick half is heavier! When you visualize the forces, it looks something like this:
When you look through the lens of physics, even a single vegetable in the supermarket becomes a gateway to a world of beautiful equations and balance. I’ve shared many more fascinating problems like this in my textbook for the Science Proficiency Test. Check it out if you’re curious!
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