From: veritasium
Professional bowling involves a complex interplay of physics, equipment, and technique to maximize the chance of knocking down all pins for a strike [00:00:10]. It is the most popular participatory sport in the United States [00:00:24].
Optimizing Pin Impact
The ideal strategy for knocking down all ten pins is not to hit the headpin squarely [00:06:23]. Hitting the headpin straight on makes a strike unlikely, potentially leading to a split where the ball goes through the middle, or the ball deflecting off to one side [00:06:29].
Instead, the chances for a strike are significantly higher if the center of the ball hits the pins just to one side of the headpin, specifically at board 17 and a half [00:06:41]. This impact causes the ball to take out the 1, 3, 5, and 9 pins, which then knock down the remaining pins [00:06:49]. The pin shape, which allows them to roll in circles like eggs, also aids in knocking down other pins [00:07:07].
For over a 90% chance of a strike, the ball’s center must hit this target with an error smaller than half a board, a difficult task when throwing 60 feet [00:07:22].
The Six-Degree Angle
Hitting the pins at an angle of six degrees, rather than head-on, dramatically increases the chances of a strike [00:07:59]. This angle widens the margin for error, allowing the ball to come in anywhere from board 17 to 18 and a half (a board and a half of room) while still maintaining over a 90% chance of a strike [00:08:07]. Achieving this angle requires curving the ball on the lane, as bowling from an angle directly proportional to this would mean bowling from a different lane entirely [00:08:26].
The Hook Shot: Skid, Hook, and Roll
The ability to curve, or “hook,” the ball is a cornerstone of modern bowling techniques [00:08:41]. This technique is primarily possible due to the intentional oiling of bowling lanes [00:09:20].
A professional bowler’s throw comprises three distinct phases:
- Skid: When the ball is released, it can travel at 20 miles per hour and spin at 500 RPM [00:10:51]. During the skid phase, the ball slides down the oiled lane, spinning but not rolling in its direction of travel [00:11:05]. Right-handers typically throw the ball to the right while spinning it to the left [00:11:00].
- Hook: As the ball reaches the end of the oiled pattern, friction with the drier lane surface increases, causing the ball to accelerate to the left (for a right-hander) and “hook” because of its spin [00:11:10].
- Roll: In the final phase, the ball’s spin aligns with its direction of travel, and it begins rolling without slipping as it barrels into the pins, ideally at the six-degree entry angle [00:11:17].
Lane Conditions and Oil Patterns
The condition of the oil on the lane is a critical factor for professional bowlers [00:14:11]. Lanes are oiled by specialized machines that can apply varying degrees of oil thickness across the lane and extend the oil pattern different distances [00:10:09]. Hundreds of different patterns can be used [00:10:23].
Generally, oil extends about two-thirds of the way down the lane (around 40-45 feet), ensuring a dry patch before the pins to increase friction and initiate the roll phase [00:10:27].
Adapting to Changing Conditions
As a game progresses, bowling balls move the oil around, pushing it further down the lane and stripping it off common paths [00:14:48]. This necessitates continuous adjustments by players to the changing lane conditions [00:14:58].
For competitive play, oil conditions vary significantly week to week, unlike league bowling where the “shot” remains consistent [00:15:38]. Different oil patterns have names like Cheetah, Chameleon, Scorpion, Shark, and Bear [00:15:47]. While some bowlers try to visually assess the oil, others rely on the ball’s reaction as their primary guide [00:14:18].
Bowling Ball Technology and Selection
Professional bowlers utilize advanced bowling ball design and technologies to enhance performance [00:00:08]. Modern bowling balls are not solid, perfect spheres; they contain internal weight blocks that are often asymmetric and not centered [00:00:47].
Internal Core Design
The internal core of a bowling ball, known as the weight block, is made of a denser material than the surrounding core of lightweight glass beads [00:01:07]. The weight block can be asymmetrically shaped, differing along the X, Y, and Z axes [00:01:11]. This internal asymmetry means that balls are heavier on one side [00:02:55].
The location of the ball’s center of gravity can be marked on its surface by letting it settle on a cushion of air [00:03:01]. Different weight blocks and their placement affect how the ball rolls [00:16:46]. If the center of mass is on the left side of the ball (for a right-hander), it pulls in the same direction as the spin, aiding the ball’s hook into the pins [00:18:27].
Radius of Gyration (RG) and RG Differential
Bowling ball design is also characterized by Radius of Gyration (RG), which describes how mass is distributed around the axis of rotation [00:17:13]. A lower RG means a lower moment of inertia, allowing the ball to spin faster for the same energy input [00:17:28]. This faster spin allows a bowler to hook the ball more sharply further down the lane, improving the chance of achieving the optimal six-degree entry angle [00:17:53].
Asymmetric cores, visible on the outside of the ball by a pin, have three different principal axes of rotation: minimum, maximum, and intermediate moment of inertia [00:19:39]. Professional bowlers drill their balls so that at launch, the axis of rotation is between the minimum and maximum moment of inertia [00:20:19]. This causes the ball to precess like a gyroscope as it travels down the lane, rotating its axis of rotation [00:20:28]. This precession means different parts of the ball contact the lane, leading to “track flare” (spread-out oil lines on the ball surface) [00:20:40]. Track flare is desirable as it ensures the ball gets traction faster and hooks more dramatically when it hits the unoiled part of the lane [00:20:52]. Asymmetric cores are designed with larger differences between their moments of inertia (RG differential) to facilitate this precession [00:21:01].
Surface Finish (Cover Stock)
The surface of the ball, or cover stock, is a critical factor affecting ball motion [00:23:05]. Reactive resin, a modified polyurethane with a porous surface, is the most popular cover stock today because it provides more grip in the oil [00:16:16].
The finish of the cover stock significantly impacts performance:
- Rougher finishes (like winter tires) provide more traction in the oil, causing the ball to hook earlier [00:23:35]. This is beneficial for long oil patterns or slower axis rotation [00:23:42]. On a dry lane, rougher exteriors can paradoxically lead to less friction because less surface area touches the lane [00:24:17].
- Smoother finishes (up to a near mirror shine) are better for short oil patterns, preventing the ball from hooking too much, too early [00:24:24].
Professional bowlers carry multiple balls to competitions, selecting a ball based on the specific lane conditions, similar to a golfer choosing a club [00:24:34].
Impact of Technology on Scores
The introduction of new bowling ball technologies has correlated with significant increases in average scores and the number of perfect 300 games [00:25:04]. For example, a dip in perfect games occurred in 1976 when “soaker balls” (chemically softened to absorb oil) were banned, but then more 300 games were hit after the introduction of the Brunswick LT-48 rubber ball [00:25:20]. A significant jump in perfect games also followed the introduction of reactive resin balls in 1991 [00:25:37].
Studies, like the USBC’s 2008 landmark study using the bowling robot Harry, have shown that the ball’s surface is the most significant factor affecting ball motion [00:22:02]. Other important factors include RG and RG differential, while the center of gravity has relatively less impact [00:22:42]. Even minute details like the color of the ball can have a small impact, as different pigments absorb oil at different rates [00:26:05].
The Complexity of a Professional Shot
A single professional bowling shot requires consideration of numerous factors [00:26:22]:
- The oil pattern on the lane and how it has shifted during the game [00:26:24].
- The weight block in the chosen ball (symmetric or asymmetric) [00:26:30].
- Which axis the ball will spin about to affect precession [00:26:33].
- The position of the center of mass to influence the ball’s pull [00:26:37].
- The cover stock material and its finish (rough or smooth) [00:26:39].
All these elements are orchestrated to execute a shot that properly skids, hooks, and rolls, hitting the pins between boards 17 and 18 and a half at an angle as close to six degrees as possible [00:26:43]. Achieving this consistently, 12 times in a row, results in a perfect game [00:26:55].