DEFINITION of 'Human Development Index-HDI'. A tool developed by the United Nations to measure and rank countries' levels of social and economic development based on four criteria: Life expectancy at birth, mean years of schooling, expected years of schooling and gross national income per capita.EFINITION of 'Human Development Index-HDI'. A tool developed by the United Nations to measure and rank countries' levels of social and economic development based on four criteria: Life expectancy at birth, mean years of schooling, expected years of schooling and gross national income per capita.
A top and bottom gear rack are moving in the same direction but with different velocities (top rack 5 m/s and bottom rack 3 m/s). What is the angular velocity of the small attached gear B at the instant shown? Assume the top rack, bottom rack, and link AB remain horizontal.
Glossary Â» Units Â» Angular Velocity Â» Revolution Per Second. Revolution Per Second (rps, rev/s) is a unit in the category of Angular velocity. It is also known as revolutions per second, revolution/second, rev/second. Revolution Per Second (rps, rev/s) has a dimension of aT-1 where T is time. It can be converted to the corresponding standard SI unit rad/s by multiplying its value by a factor of 6.28318530718.