Which statement best describes the effects of drought, desertification, and erosion on the people who live in the sahel on the edge of the sahara desert?

a)these factors have led to warfare between tribes in the region. b)these factors have caused a great migration of people from the region. c)these factors have caused the united nations to declare the region endangered. d)these factors have led to hunger in the region because of a lack of arable land.

Ireally need this answer sombody fast fast

Aboat radioed a distress call to a coast guard station. at the time of the call, a vector a from the station to the boat had a magnitude of 45.0 km and was directed 15.0° east of north. a vector from the station to the point where the boat was later found is = 30.0 km, 15.0° north of east. what are the components of the vector from the point where the distress call was made to point where the boat was found? in other words, what are the components of vector c = b - a?

Consider a double atwood machine constructed as follows: a mass 4m is suspended from a string that passes over a massless pulley on frictionless bearings. the other end of this string supports a second similar pulley, over which passes a second string supporting a mass of 3m at one end and m at the other. using two suitable generalized coordinates, set up the lagrangian and use the lagrange equations to find the acceleration of the mass 4m when the system is released. explain why the top pulley rotates even though it carries equal weights on each side.