Near Field Communication is an umbrella term that applies to location-aware technologies that allow devices to communicate securely with each other over short distances. Near-field communication is a short-range wirelessconnectivity standard that uses magnetic field induction to enable communication between devices when they're touched together, or brought within a few centimeters to each other.It also specifies a way for the devices to establish a peer-to-peer network to exchange data. After the peer to peer network has been configured, another wireless communication technology, such as Bluetooth or Wi-Fi, can be used for longer-range communication or for transferring larger amounts of data.
Because the mechanical advantage of the machine is affected by friction and weight but velocity ratio is not. So, mechanical advantage is less than velocity rate. Thus, the machine's efficiency is less than 100% and can't be a perfect machine
