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.
A rack is a toothed bar or rod that can be thought of as a sector gear with an infinitely large radius of curvature. 1  Pitch: 16 to 96 DP & 1.5 to .25 MOD. 2  Material: Aluminum and Stainless Steel. 3  Available in Round or Rectangular Design.