A person jumping or diving off a tall building or a cliff can do so in many different ways. However, if the only launch platform available is relatively narrow or bounded by a fence nearby, then a standing jump or dive may be the only option. A wider ledge might allow for one or two steps before jumping or diving. In that case, a typical horizontal launch speed for a person of average athletic ability would be 2–3 m/s. A good swimmer can dive into a swimming pool at about 4 m/s by pushing horizontally against a vertical surface such as the starting block. Each of these speeds is larger than the speed at which a person can be pushed, so it is theoretically possible to distinguish between a push and a jump or dive under these conditions. However, a launch speed of 2 m/s or less does not allow for such a distinction, at least in terms of the estimated launch speed.