While on a car trip of 1000 km, you travel half of the distance at 90 km/hr and the other half at 60 km/hr. On the return trip, you travel half the time at 90 km/hr and the other half at 60 km/hr. What is your average speed for the entire trip (in km/hr)?

Tornadoes form in unusually violent thunderstorms when there is sufficient (1) instability and (2) wind shear present in the lower atmosphere. elaborate on what does instability mean when discussing the formation of a tornado? a) dry air in the middle atmosphere being rapidly cooled by rain b) winds at all levels of the atmosphere are strong and turn with height c) an isolated strong thunderstorm just ahead of a squall line that merges with the squall line d) very warm, humid conditions in the lower atmosphere; cooler than usual conditions in the upper atmosphere