In this blog entry I consider how slingshots stack up against other other common human powered sports. I have selected a number of sports that involve a human flinging a ball, from golf to the shotput, from soccer to Jai-alai. Slingshots possess the least kinetic energy of all these sports. They aren't the fastest either. However, slingshot projectiles are the most accurate and most dense.
The Physics
Consider the kinetic energies involved. To do so, we measure the velocity and mass and apply the formula:
kinetic energy = 0.5 x mass x velocity x velocity.
Golf: 84m/s, 0.046kg, 162J driver, good connection
Tennis: 69m/s, 0.075kg, 180J fast serve
Soccer: 40m/s, 0.43kg, 348J penalty kick
Jai-alai: 84m/s, 0.140kg, 494J fast indoor ball game
Shot put: 15m/s, 7.26kg, 817J competitive, but not olympian throw
Analysis
Let's crunch the numbers and shot it as a chart.
Discussion
Slingshots Have Little Kinetic Energy
I recognise that the slingshot described above is not the most powerful ever made, but it is typical of the type that is most commonly banned when bans are legislated. Even really efficient slingshots only deliver around 12J, which as you can see remains insignificant against the other sports in terms of kinetic energy.
Projectile Hardness
In some cases, especially the inflated balls, the lower density and hardness and greater resilience mean they may knock you over and maybe even concuss you, but you'll probably get away without serious injury if you get hit. For example, nobody has ever been penetrated by a tennis ball (at least I hope not; please do not invoke Internet Rule 34).
Projectile Density
The denser and harder the projectile the more damage it is likely to do. I am sure many people have seen someone get a deep bruising or a broken nose from a stray baseball. Indeed, quite a few people have been seriously injured or killed by golf balls in the history of the sport.
Worst Case Scenario - A Golf Ball to the Head
Let's take a closer look at getting hit by a golf ball. Here's a particularly ugly scenario; imagine there is a vertically staggered tee arrangement, with the red tee almost directly in front and some 5 feet below the whites. A male golfer takes a Mulligan or provisional shot just as a lady steps up to address the ball and her head pops up just over the front of the men's tee directly into the flight path of the ball. It's a cracking good shot from a driver and she takes one to the head. Let's say the clubhead speed was typical for a driver at '125mph' and that the ball left the face at 1.5x the clubhead speed, giving 84m/s. The golf ball weighs 46g. No significant energy is lost in flight and the impact transfers all the kinetic energy to the lady's head. That's a whopping 162J, dwarfing a typical slingshot by more than an order of magnitude. A golf ball is a small, dense and hard ball. I know this is almost a worst case scenario, but precisely this once happened to a former colleague of mine and my friend now sports a snazzy star-shaped Harry Potter scar where the ball shattered her skull. She is lucky that she took it to the forehead at the hairline. A full on hit to a thinner section of skull would have resulted in penetration and quiet likely a fatality.
Even Worse Case Scenarios
Upping the stakes yet further, a Jai Alai Pelota is 3/4 the size of a baseball, harder than a golf ball, and has been clocked at speeds in excess of 180 mph. It makes John Daly's golf drive look like a spitball, with nearly 500J (almost 100 times the kinetic energy of a slingshot). I don't need to describe what would happen if you took one to the head and that's only half the energy of a shot put (800+J).
Slingshots Still Demand Respect
Of course, that doesn't mean sIingshots don't require a great deal of respect. Slingshots, especially with lead or steel pellets are more efficient at penetrating flesh (or at least ballistic gelatin) than even a golf ball or jai-alai pelota.
Fortunately, the injuries sustained by some members of the community have shown injury to the cutaneous and connective tissues at the impact site, but have not broken underlying bones or reached a vital organ or major blood vessel. The only fatality I have come across in my research involved a young boy hit in the chest with a large rock shot from some tubes tied to posts at a playground. While highly regrettable, this very different to the typical use of a toy or target shooting slingshot.
Nevertheless, be aware that severe injuries can happen during slingshot shooting. A band slap to the eye, a hand hit, or a miss or ricochet can be painful and/or dangerous. Just like every sport in the chart above, slingshot shooting should be carried out responsibly and under competent supervision and all appropriate safety gear and precautions should be taken. Let's keep our sport as safe as possible.
That's beyond my expertise, but the masses, forces and energies involved are much higher; in the hundreds of joules, certainly. Here are some links, courtesy of google.
In this blog entry I consider how slingshots stack up against other other common human powered sports. I have selected a number of sports that involve a human flinging a ball, from golf to the shotput, from soccer to Jai-alai. Slingshots possess the least kinetic energy of all these sports. They aren't the fastest either. However, slingshot projectiles are the most accurate and most dense.
The Physics
Consider the kinetic energies involved. To do so, we measure the velocity and mass and apply the formula:
kinetic energy = 0.5 x mass x velocity x velocity.
Golf: 84m/s, 0.046kg, 162J driver, good connection
Tennis: 69m/s, 0.075kg, 180J fast serve
Soccer: 40m/s, 0.43kg, 348J penalty kick
Jai-alai: 84m/s, 0.140kg, 494J fast indoor ball game
Shot put: 15m/s, 7.26kg, 817J competitive, but not olympian throw
Analysis
Let's crunch the numbers and shot it as a chart.
Discussion
Slingshots Have Little Kinetic Energy
I recognise that the slingshot described above is not the most powerful ever made, but it is typical of the type that is most commonly banned when bans are legislated. Even really efficient slingshots only deliver around 12J, which as you can see remains insignificant against the other sports in terms of kinetic energy.
Projectile Hardness
In some cases, especially the inflated balls, the lower density and hardness and greater resilience mean they may knock you over and maybe even concuss you, but you'll probably get away without serious injury if you get hit. For example, nobody has ever been penetrated by a tennis ball (at least I hope not; please do not invoke Internet Rule 34).
Projectile Density
The denser and harder the projectile the more damage it is likely to do. I am sure many people have seen someone get a deep bruising or a broken nose from a stray baseball. Indeed, quite a few people have been seriously injured or killed by golf balls in the history of the sport.
Worst Case Scenario - A Golf Ball to the Head
Let's take a closer look at getting hit by a golf ball. Here's a particularly ugly scenario; imagine there is a vertically staggered tee arrangement, with the red tee almost directly in front and some 5 feet below the whites. A male golfer takes a Mulligan or provisional shot just as a lady steps up to address the ball and her head pops up just over the front of the men's tee directly into the flight path of the ball. It's a cracking good shot from a driver and she takes one to the head. Let's say the clubhead speed was typical for a driver at '125mph' and that the ball left the face at 1.5x the clubhead speed, giving 84m/s. The golf ball weighs 46g. No significant energy is lost in flight and the impact transfers all the kinetic energy to the lady's head. That's a whopping 162J, dwarfing a typical slingshot by more than an order of magnitude. A golf ball is a small, dense and hard ball. I know this is almost a worst case scenario, but precisely this once happened to a former colleague of mine and my friend now sports a snazzy star-shaped Harry Potter scar where the ball shattered her skull. She is lucky that she took it to the forehead at the hairline. A full on hit to a thinner section of skull would have resulted in penetration and quiet likely a fatality.
Even Worse Case Scenarios
Upping the stakes yet further, a Jai Alai Pelota is 3/4 the size of a baseball, harder than a golf ball, and has been clocked at speeds in excess of 180 mph. It makes John Daly's golf drive look like a spitball, with nearly 500J (almost 100 times the kinetic energy of a slingshot). I don't need to describe what would happen if you took one to the head and that's only half the energy of a shot put (800+J).
Slingshots Still Demand Respect
Of course, that doesn't mean sIingshots don't require a great deal of respect. Slingshots, especially with lead or steel pellets are more efficient at penetrating flesh (or at least ballistic gelatin) than even a golf ball or jai-alai pelota.
Fortunately, the injuries sustained by some members of the community have shown injury to the cutaneous and connective tissues at the impact site, but have not broken underlying bones or reached a vital organ or major blood vessel. The only fatality I have come across in my research involved a young boy hit in the chest with a large rock shot from some tubes tied to posts at a playground. While highly regrettable, this very different to the typical use of a toy or target shooting slingshot.
Nevertheless, be aware that severe injuries can happen during slingshot shooting. A band slap to the eye, a hand hit, or a miss or ricochet can be painful and/or dangerous. Just like every sport in the chart above, slingshot shooting should be carried out responsibly and under competent supervision and all appropriate safety gear and precautions should be taken. Let's keep our sport as safe as possible.
That's beyond my expertise, but the masses, forces and energies involved are much higher; in the hundreds of joules, certainly. Here are some links, courtesy of google.
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