Have you ever heard the story that a penny dropped from the Empire State Building could seriously hurt or even kill someone on the ground? It’s a popular urban legend, but is it true? Derek and Adam Savage, one of the original MythBusters, decided to find out by conducting an experiment. Let’s explore what they discovered and learn about the science behind falling objects.
To test the myth, Derek and Adam used a helicopter to drop pennies from high above. Adam dropped the pennies while Derek observed from below. They wanted to see if a penny, which weighs about 2.5 grams, could become dangerous when dropped from the Empire State Building, which is 443 meters tall.
A key idea in this experiment is terminal velocity. This is the fastest speed an object can reach when falling through the air. Air resistance plays a big role here. Without air resistance, a penny could theoretically reach speeds over 300 kilometers per hour, about half the speed of a bullet. However, because of air resistance, a penny’s actual terminal velocity is much lower, around 80 kilometers per hour.
As the helicopter hovered, Derek prepared for the penny drops. The first few pennies were dropped to see where they would land. Derek described it as nerve-wracking because the helicopter’s downdraft made things unpredictable. When the pennies hit Derek, they stung a bit but were far from lethal.
The experiment showed how air resistance affects falling objects. Derek explained that air resistance depends on an object’s shape and weight. For example, on the moon, where there’s no air, a hammer and a feather would fall at the same speed. But on Earth, air resistance slows the feather down, showing how terminal velocity works.
Derek and Adam also looked at how an object’s shape and weight affect its terminal velocity. While a penny has a low terminal velocity, other objects like hailstones can fall much faster because they are heavier and larger. Hailstones can reach speeds over 200 kilometers per hour, making them potentially dangerous.
Next, they tested another myth: could a ballpoint pen be deadly if dropped from a great height? Since a pen is heavier than a penny and has a smaller surface area, it might fall faster. They used a ballistics gel dummy for safety. The results showed that pens weren’t a significant threat, debunking this myth too.
Derek and Adam’s experiment showed that while a penny or a pen dropped from a skyscraper isn’t likely to cause serious harm, other objects with more mass and better aerodynamic properties can be dangerous. Larger objects like baseballs or hailstones can have enough energy to cause injury or even death.
In conclusion, the myth that a penny dropped from the Empire State Building could kill someone has been debunked. Understanding terminal velocity and air resistance helps explain why some objects aren’t as dangerous as they might seem when falling from great heights.
Let’s explore terminal velocity by creating a simple experiment. Use a coffee filter and a stopwatch. Drop the coffee filter from a height and time how long it takes to reach the ground. Repeat the experiment with a crumpled piece of paper of similar weight. Discuss why the times are different and how air resistance affects each object.
Calculate the speed of a penny falling from the Empire State Building. Use the formula for terminal velocity: $$v = sqrt{frac{2mg}{rho C_d A}}$$ where $m$ is mass, $g$ is gravity, $rho$ is air density, $C_d$ is drag coefficient, and $A$ is cross-sectional area. Discuss how each variable affects the speed.
Watch a clip from the MythBusters episode where they test the penny myth. Take notes on the experiment setup and results. Discuss in groups whether the experiment was convincing and what you learned about air resistance and terminal velocity.
Design an experiment to test the effect of shape on terminal velocity. Use different objects like a flat sheet of paper, a crumpled paper ball, and a paper airplane. Predict which will fall fastest and why. Conduct the experiment and compare results with your predictions.
Write a short story imagining you are a penny dropped from the Empire State Building. Describe your journey, the forces acting on you, and what happens when you reach the ground. Use scientific terms like “air resistance” and “terminal velocity” in your narrative.
Penny – A small, flat, round piece of metal used as currency, often used in physics experiments to demonstrate concepts like gravity and air resistance. – In our physics class, we dropped a penny from the top of the building to study how air resistance affects its fall.
Experiment – A scientific procedure undertaken to test a hypothesis by collecting data and observing outcomes. – The students conducted an experiment to see how different surfaces affect the speed of a rolling ball.
Terminal – Referring to the final stage or point, often used in physics to describe terminal velocity, which is the constant speed that a freely falling object eventually reaches when the resistance of the medium prevents further acceleration. – When a skydiver reaches terminal velocity, the force of gravity is balanced by air resistance, and they fall at a constant speed.
Velocity – The speed of something in a given direction, often represented as a vector quantity in physics. – The velocity of the car was measured at $60 , text{m/s}$ heading north.
Air – The invisible gaseous substance surrounding the Earth, a mixture mainly of oxygen and nitrogen, which can exert resistance on moving objects. – Air resistance is a force that acts against the motion of an object moving through the air.
Resistance – A force that opposes or slows down motion, often encountered in physics as air resistance or friction. – The resistance from the water made it difficult for the swimmer to move quickly.
Shape – The external form or appearance of an object, which can affect its motion and behavior in physical experiments. – The shape of an airplane’s wings is designed to reduce air resistance and increase lift.
Weight – The force exerted on an object due to gravity, calculated as the product of mass and gravitational acceleration ($W = mg$). – The weight of the object was measured to be $9.8 , text{N}$ on Earth.
Objects – Things that can be seen and touched, which have mass and occupy space, often studied in physics to understand motion and forces. – In the lab, we observed how different objects fall at the same rate in a vacuum.
Science – The systematic study of the structure and behavior of the physical and natural world through observation and experiment. – Science helps us understand the principles behind everyday phenomena, like why the sky is blue.
