Find the work (in ft-lb) done by winding up a hanging cable of length 100 ft and weight-density 3 lb/ft. ft-lb How much work (in ft-lb) is done to lift the cable 50 ft?

Ahollow metal sphere has 6 cm and 11 cm inner and outer radii, respectively. the surface charge density on the inside surface is −100nc/m2. the surface charge density on the exterior surface is:

Ascientist wants to test ways to reduce pollution in lake . what is the bestway of doing this

The star nearest to our sun is proxima centauri, at a distance of 4.3 light-years from the sun. how far away, in km, is proxima centauri from the sun?