Why is ketchup so hard to pour? - George Zaidan

Summary

This video explores the peculiar behavior of ketchup as a non-Newtonian fluid, contrasting it with Newtonian fluids like water. Ketchup’s flow changes based on the force applied—becoming thinner when pushed hard and flowing slowly when pressed gently for a long time. Its complex behavior arises from the tomato particles suspended in liquid, making it harder to pour than expected. The video delves into the science behind ketchup's flow and suggests two methods to successfully pour it—either through strong, quick force or slow, continuous shaking.

Takeaways

• 🍟 Ketchup is a non-Newtonian fluid, meaning its flow behavior depends on the amount of force applied.
• 🍅 Ketchup is made from pulverized tomato particles suspended in a mixture of water, vinegar, sugar, and spices.
• 🧪 When you apply a weak force to ketchup, it behaves like a solid because the particles bump into each other and can't move.
• 💪 Applying a strong force can cause the ketchup to thin and flow as the particles are squeezed and rearranged.
• ⏳ Even with weak force, ketchup can flow over time as particles shift, possibly due to the water acting as a lubricant.
• 🔬 Scientists are still researching how ketchup and other non-Newtonian fluids behave under different conditions.
• 📏 Ketchup shows two main properties: thinning when a certain force threshold is reached and more gradual thinning with prolonged weak force.
• 🥄 Other non-Newtonian fluids like oobleck or natural peanut butter behave differently, sometimes becoming thicker with force.
• 🍴 Different brands of ketchup may behave differently due to variations in ingredients and thickeners like xanthan gum.
• 👌 The best way to pour ketchup is to give the bottle short, sharp shakes before a controlled pour, ensuring the right consistency.

Q & A

Why is it difficult to pour the exact right amount of ketchup?

Ketchup is a non-Newtonian fluid, meaning its thickness changes based on how much force is applied. This makes it hard to control the flow and pour the exact right amount.

What are Newtonian fluids, and how do they behave?

Newtonian fluids, like water, oils, and alcohols, respond to force linearly. If you push them twice as hard, they move twice as fast, following Sir Isaac Newton's law.

What makes ketchup a non-Newtonian fluid?

Ketchup responds to force non-linearly. It gets thinner when you apply a higher force, and it also flows after a weak force is applied for a long time. These two behaviors make it non-Newtonian.

What are some examples of other non-Newtonian fluids?

Other non-Newtonian fluids include mayonnaise, toothpaste, blood, paint, and peanut butter. These fluids also change their thickness depending on how hard or how long force is applied.

How does ketchup behave when force is applied quickly?

When a strong force is applied quickly, the tomato particles in ketchup get smushed, creating space for the particles to move past each other, which makes the ketchup flow.

What happens when a weak force is applied to ketchup for a long time?

With a weak force applied for a long time, ketchup can slowly start to flow. Scientists are unsure exactly why, but one possibility is that the tomato particles rearrange or the liquid near the edges acts as a lubricant.

How do ingredients like xanthan gum affect the behavior of ketchup?

Xanthan gum and other thickeners can alter the balance of ingredients in ketchup, which means different ketchups can behave differently, even though they are all non-Newtonian.

What are the two ways to get ketchup out of a bottle according to the script?

You can either apply a long, slow, steady force to gradually make the ketchup flow, or hit the bottle once very hard to quickly break the ketchup's resistance.

What method do 'pros' use to pour ketchup effectively?

Pros shake the bottle with the lid on a few times to loosen the particles, then remove the lid and pour with controlled precision.

Why do scientists continue to study ketchup and other non-Newtonian fluids?

Non-Newtonian fluids like ketchup exhibit complex behaviors that are still not fully understood, especially regarding how their particles interact over time and under different forces.