99% People Get This Wrong! Which Ball Hits the Ground First? Brain Test Challenge
Can you solve this tricky physics brain teaser?
Two balls (A & B) are cut at the exact same time — but which one will touch the ground first? It looks simple… but there’s a hidden concept most people miss!
Only sharp minds can figure this out correctly.
At first glance, the riddle presented in the image seems straightforward: two identical balls, Ball A and Ball B, are suspended from a wooden beam and are about to be released simultaneously by a pair of scissors cutting their supports. The only difference is their connection mechanism—Ball A is attached via a coiled spring, while Ball B hangs from a rigid, straight string or wire.
Let’s break down every possibility simply.
Scenario 1: The Ideal Physics Answer (Winner: Ball A)
If you see this riddle on an IQ test or a physics forum, the intended correct answer is almost always Ball A.
To understand why, we need to look at what happens the exact millisecond before and after the cut.
The Magic of Stretched Springs
When Ball A hangs from the spring, its heavy weight stretches the spring downward. This creates elastic potential energy. The spring desperately wants to snap back to its original, shorter coiled shape. It is pulling up on the ball, while the ball is pulling down on the spring.
The “Sling-Shot” Effect
The moment the scissors cut the wire above the spring, the spring is suddenly freed from the ceiling.
For Ball B: The string has no elasticity. Once cut, it enters a state of free fall. It doesn’t push or pull Ball B; it just falls alongside it at the standard speed of gravity.
For Ball A: The spring is no longer anchored to the ceiling, but it is still stretched. Because it wants to contract instantly, the top of the spring collapses downward toward its center, while the bottom of the spring pulls upward? No, actually, it is even more fascinating.
When a extended spring is released from the top, the tension inside the spring pulls its ends together. Because the top is free and the bottom is held down by the heavy ball, the top of the spring collapses downward incredibly fast. As it contracts, it actually applies an extra downward force or transfers its contracting momentum toward the ball.
More simply put: Ball B only has gravity pulling it down. Ball A has gravity pulling it down PLUS the contracting force of the spring pulling/collapsing downward behind it. This contraction acts like a tiny extra engine, accelerating Ball A toward the ground faster than mere gravity alone. Therefore, Ball A hits the ground first.
Scenario 2: The Real-World Practicality (Winner: Ball B)
While the physics textbook says Ball A wins, an engineer or a realist might argue that Ball B will touch the ground first in real life. Why? Because of physical dimensions and how we define “touching the ground.”
The “Squeezing” Problem
Look closely at the image. Both balls are hanging at the exact same level.
When the wire above the spring is cut, the spring immediately begins to contract (shrink). Even though the center of mass of system A might accelerate faster, the spring itself is actively shrinking in length. It is pulling itself upward toward the ball just as much as it is collapsing downward.
Because the spring shortens instantly, it effectively “lifts” or holds the ball slightly higher relative to the top of the spring during the initial collapse.
The Length Advantage
More importantly, look at the length of the attachments:
Ball B is attached to a very long, unyielding string.
Ball A is attached to a spring, meaning the actual ball starts at the exact same height as B, but the distance between the ball and the cut is filled with a bouncy coil.
In real life, a rigid string does not shrink. The moment it is cut, Ball B drops instantly from its current position. If the spring on Ball A recoils upward even a fraction of an inch as it snaps back together, it delays the bottom of the ball from reaching the floor. Furthermore, if the spring vibrates or bounces erratically on the way down, it wastes energy moving sideways instead of straight down. Therefore, in a real-world experiment, Ball B often touches the floor first because its support doesn’t deform or shrink.
Scenario 3: The “Perfectly Rigid” Trap (It’s a Tie!)
There is a third, highly theoretical way to look at this. What if we ignore the spring’s contraction and the string’s weight entirely?
If we assume the spring is already fully collapsed (which it isn’t in the picture) or that the mass of the spring and string is zero, then both objects become subject to Galileo’s famous law of gravity: all objects fall at the same rate regardless of their mass.
If you drop a feather and a bowling ball in a vacuum, they hit the ground at the same time. If we treat the spring and string as weightless lines that instantly disappear after being cut, both Ball A and Ball B are simply falling from the exact same height under the influence of regular gravity ($9.8\text{ m/s}^2$). Under these idealized conditions, it would be a dead tie.
