Metrication in the United States There are no U.S. customary units for electric current, potential difference, or charge since these concepts were developed after the international adoption of metric in science. The metric units ampere, volt, ohm and coulomb are the only units used. The SI term hertz has replaced the term "cycles per second" as a unit of frequency. Energy is often measured in watt hours, BTUs, therms or calories rather than the SI joule. Residential and commercial electrical energy use is metered and billed in kilowatt hours, kW·h, as in most metric countries. Force measurements regularly use the pound instead of the SI
Inch per second Inch per second The inch per second is a unit of speed or velocity. It expresses the distance in inches ("in") traveled or displaced, divided by time in seconds ("s", or "sec"). The equivalent SI unit is the metre per second. Abbreviations include in/s, in/sec, ips, and less frequently in s. 1 inch per second is equivalent to: 1 metre per second ≈ 39.370079 inches per second (approximately)<br> 1 foot per second = 12 inches per second (exactly)<br> 1 mile per hour = 17.6 inches per second (exactly)<br> 1 kilometre per hour ≈ 10.936133 inches per second (approximately) In magnetic