1 XL â or EXL, Exploration Licence (United Kingdom), a type of onshore licence issued between the First Onshore Licensing Round (1986) and the Sixth (1992). 2  Xln â Crystalline (minerals). 3  XLPE-Cross-linked Polyethylene. 4  XMAC â Cross-Multipole Array Acoustic log.
When the frequency approaches 120 CPM (2 Hz), occupants perceive the ride as harsh. Consequently, the suspension of the average family sedan will have a natural frequency of about 60 to 90 CPM. A high-performance sports car will have a stiffer suspension with a natural frequency of about 120 to 150 CPM (2 to 2.5 Hz). Originally, human sensitivity to ride frequency was believed to be associated with the natural oscillations of an adult human body during a walking gait.
An average Formula E car has a power of at least 250 horsepower (190 kW). The car is able to accelerate from 0â100 km/h (0â62 mph) in 3 seconds, with a maximum speed of 225 km/h (140 mph). The noise levels are approximately 80 dB (SPL), which is more than an average petrol car which produces about 70 dB.