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 and pinion is a pair of gears which convert rotational motion into linear motion. The circular pinion engages teeth on a flat bar - the rack. Rotational motion applied â¦to the pinion (by the steering wheel) will cause the rack to move to one side or the other, right up to the limit of its travel. The rack and pinion arrangement is commonly found in the steering mechanism of cars or other wheeled, steered vehicles.