The sight and sound that occur when you rub two pennies together are familiar to many. But have you ever wondered what’s happening when you rub two pennies against each other? Why does it make that scraping noise? And does it do any damage to the coins?

If you’re short on time, here’s a quick answer to your question: Rubbing two pennies together scrapes off small amounts of metal through friction and abrasion, which produces a scraping noise. It doesn’t significantly damage the coins.

In this comprehensive guide, we’ll explore what happens on a chemical and physical level when you rub two pennies together. We’ll look at the metals in pennies, the science of friction, and whether this can damage or permanently alter pennies.

We’ll also discuss the history of the penny and alternative uses for spare change.

Composition of Pennies

Have you ever wondered what happens when you rub two pennies together? Before we delve into the fascinating reaction, let’s first understand the composition of pennies.

Pennies Are Made of Zinc and Copper

Pennies in circulation today are primarily composed of zinc and copper. The outer layer of a penny is made up of copper, while the core is made of zinc. This composition gives pennies their distinct reddish-brown color. Each penny contains 97.5% zinc and 2.5% copper.

The use of these metals ensures that pennies are durable and long-lasting.

When you rub two pennies together, you might notice some changes in their appearance. Due to the friction between the two coins, the copper coating may wear off, revealing the silver-colored zinc underneath.

This phenomenon is known as “abrading” and is a result of the softer copper layer being worn away by the rubbing action.

Pennies Used to Be Made of Bronze

It’s interesting to note that pennies used to be made of a different composition. Before 1982, pennies were made of bronze, which is an alloy of copper and tin. This composition gave the coins a darker brown color and a slightly different weight compared to modern pennies.

The change in composition was mainly driven by economic factors. As the price of copper started to rise, it became more cost-effective to produce pennies using a zinc core with a thin copper plating. This switch in materials allowed for the continued production of pennies while reducing manufacturing costs.

To learn more about the composition of pennies and their history, you can visit the United States Mint website. The Mint provides valuable information and resources on various aspects of coin production and history.

Friction When Rubbing Pennies

What Happens When You Rub Two Pennies Together?

When two pennies are rubbed together, friction is created. Friction is the force that resists the motion between two surfaces in contact. In this case, the two surfaces are the pennies. Friction occurs because the irregularities on the surface of the pennies interlock with each other, making it more difficult for them to slide past one another.

Friction Generates Heat and Abrasion

As the two pennies rub against each other, the friction generates heat. This is because the energy from the rubbing motion is converted into thermal energy. If you have ever rubbed your hands together vigorously, you may have noticed that they start to feel warmer.

The same principle applies when rubbing pennies together.

In addition to heat, friction can also cause abrasion on the surface of the pennies. The constant rubbing motion can wear down the top layer of the pennies, resulting in small scratches or marks. Over time, repeated rubbing can even cause the pennies to lose some of their original shine.

Making Pennies Slide Easier with Lubrication

To reduce friction between the pennies and make them slide easier, lubrication can be used. Lubricants are substances that are applied to surfaces to reduce friction between them. Common lubricants include oils, greases, and waxes.

By applying a small amount of lubricant to the pennies, the friction between them is minimized, allowing them to slide past each other more smoothly.

It’s important to note that rubbing pennies together is more of a fun experiment rather than a practical application. However, understanding the concept of friction and how it affects objects in contact can help us comprehend various real-world scenarios, such as the performance of moving parts in machinery or the importance of proper lubrication for smooth operation.

The Scraping Noise

Have you ever wondered what happens when you rub two pennies together? One of the first things you’ll notice is the distinctive scraping noise that occurs. This noise is a result of the vibrations created when the two coins come into contact with each other and rub against their rough surfaces.

Vibrations Against Rough Surfaces

When you rub two pennies together, the ridges and imperfections on their surfaces create friction. This friction causes the coins to vibrate against each other, which in turn generates the scraping noise you hear.

The rough texture of the pennies’ surfaces amplifies the vibrations, making the noise more pronounced.

The vibrations produced by rubbing the pennies together are similar to the vibrations created when you run your fingernail along the edge of a credit card or scrape a fork against a plate. In all these instances, the rough surfaces and the pressure applied create friction, resulting in vibrations and the accompanying noises.

Similar Noises from Other Objects

The scraping noise you hear when rubbing two pennies together is not unique to coins. Many other objects can produce similar noises when rubbed against each other. For example, rubbing two pieces of sandpaper together or dragging a chair across a tiled floor can create a scraping sound.

It’s interesting to note that the pitch and intensity of the scraping noise can vary depending on the materials and textures of the objects being rubbed together. For instance, rubbing two smooth plastic surfaces might produce a softer and higher-pitched noise compared to rubbing two rough metal surfaces.

If you’re curious to learn more about the science behind these scraping noises, websites like Scientific American or Live Science can provide further insights into the topic.

Does Rubbing Pennies Damage Them?

Many people have wondered what happens when you rub two pennies together. One common concern is whether this rubbing can damage the pennies. Let’s explore this topic and find out if there are any long-term effects.

Pennies Are Resilient to Abrasion

When you rub two pennies together, you might expect to see some noticeable wear and tear. However, pennies are quite resilient to abrasion. This is because they are made of a durable metal alloy called copper-plated zinc.

The copper plating on the outside protects the zinc core from being easily damaged.

So, even if you rub two pennies together vigorously, you may not see any significant changes in their appearance. The copper plating is designed to withstand everyday use, including being handled and exchanged frequently.

It’s worth noting that older pennies made of solid copper may show more signs of wear when rubbed together. This is because solid copper is softer and more prone to scratches and abrasion. However, modern pennies are not made of pure copper, so the impact of rubbing is minimal.

Long-Term Effects Are Minimal

While rubbing pennies together may not cause immediate damage, you might wonder if there are any long-term effects. The truth is, that the long-term impact of rubbing pennies together is minimal.

As mentioned earlier, pennies are made of a copper-plated zinc alloy. The thin layer of copper on the outside provides protection and helps to maintain the integrity of the coin. Rubbing two pennies together is unlikely to wear away this protective layer significantly.

It’s important to note that coins are generally designed to be durable and long-lasting. They are manufactured to withstand handling and normal wear and tear. Rubbing pennies together is not likely to have a significant impact on their overall condition.

Alternative Uses for Spare Pennies

Decorative Crafts and DIY

Have a jar full of spare pennies lying around? Why not put them to use in some creative and decorative crafts? Pennies can be used to create unique and eye-catching artwork, such as mosaic designs or even jewelry.

With a little bit of creativity and some glue, you can transform those ordinary pennies into stunning pieces of art. Not only will this give you a chance to showcase your artistic skills, but it’s also a great way to upcycle and repurpose items you already have at home.

Good Luck Charms

Believe it or not, pennies have long been considered a symbol of good luck in various cultures. Many people believe that finding a penny, especially one that is headed up, brings good fortune. Some even keep a lucky penny in their pocket or wallet for good luck throughout the day.

So, instead of tossing those spare pennies aside, why not keep them as good luck charms? You never know, that little piece of copper might just bring a smile to your face and some good luck your way! 

Teaching Tools for Math

Pennies can also serve as valuable teaching tools, particularly in mathematics education. They can be used to teach young children about counting, addition, and subtraction. By using pennies as manipulatives, children can gain a visual and tactile understanding of these mathematical concepts.

Furthermore, pennies can be used to introduce the concept of money and its value. Teachers can create engaging activities and games using pennies to make learning math more fun and interactive.

For more information on alternative uses for spare pennies, you can visit The Spruce Crafts.

What Happens When You Rub Two Pennies Together – Conclusion

When you rub two pennies together, the friction scrapes off small amounts of metal, causing microscopic abrasions on the surface. This generates vibration and noise. While pennies can withstand a good amount of rubbing, eventually it does cause wear. But normal rubbing is harmless for casual use.

Pennies aren’t as commonly used today, but can still serve decorative and educational purposes. Understanding what happens when you fidget and play with spare change reveals the scientific forces at work in an everyday object.

So next time you rub two pennies together, appreciate the rich physics and history behind this timeless activity.

Similar Posts