This is not a game. It does not use your accelerometer.It does not use your GPS.You have to tap the screen as you pass markers to calculate accurate speed.Velocity is a simple application for the iPhone and iPod Touch you can use to determine just how fast you are going. It does not require or use any of that newfangled GPS stuff that most speedometer applications rely upon, and it will run on any iPhone or iPod Touch with software version 2.0 or greater. To have Velocity tell you how fast you are going, all you need is to pass some evenly spaced markers and tap the screen with your finger.In physics, velocity is defined as the rate of change in position. So, if you happen to notice that your positition is a-changin', and you want to know how fast you're moving, here's how: look around for something that is spaced evenly - mile markers on the side of the road, for example. As you pass these markers, press the Marker button on your iPhone/iPod. You'll notice that your measurements begin to appear on the screen. When you pass the last marker you wish to measure, press the End button. All your Marker measurements are displayed along with a summary of how far you traveled and at what speed, etc.Times this may be very useful: When terrorists are chasing you and you need to make sure you'll have enough fuel to keep driving at your current speed long enough to outrun them (and your dash-based speedo has a bullet hole in it). In this case, you had better have a passenger do your tapping for you - you need all the concentration you have to dodge that small-arms fire. You happen to be running in a 100 meter dash, and you want to know not only how fast you run the 100 meters, but just how fast you are covering each and every meter. In this case, you better be ready to tap that finger fast (or run really slow). When you are flying in your new stuntplane just above the tops of trees that you happened to plant years ago exactly 1 nautical mile apart from each other. In this case you should have your copilot tap for you - trees have a way of getting taller when you fly over them. You stumble upon Noah's ark, and want to know how fast you can walk around it as measured in cubits / hour. It's up to you to know how long a cubit is if Noah did not leave his cubit-markings on the lumber when he built it. When you bust out that skateboard you used to shred on in high school, and you happen to know that each and every crack in your sidewalk is spaced exactly 1 yard apart. You may want to have a buddy either tap for you or skate for you. You find yourself at the racetrack and wonder just how fast those horses really run. Yes, you can measure in Furlongs. Your snorkeling trip has been interrupted by sharks with lasers, and as you swim away you want to know just how fast you are moving. Switch the measure mode to leagues and swim as fast as you can. (Remember to keep the hand with your iPhone out of the water - you wouldn't want to get that wet.)Velocity can also be used to convert your speeds among 9 units of measure: Miles, Feet, Yards, Meters, Kilometers, Nautical Miles, Leagues, Furlongs and Cubits, and 6 units of time: Seconds, Minutes, Hours, Days, Weeks, Years. All conversions are done on the fly as soon as you change your units of measure, and you can go from any unit to any other unit. Ever wonder how many cubits per hour you'll cover when you are traveling at 90 furlongs per week? Velocity knows.Please note that Velocity is intended for entertainment purposes only, and should not be used in situations where distractions could be dangerous. Please measure your velocity responsibly.If you have any questions regarding Velocity, please send email to email@example.com.