Focal lengths ii if you were handed an unmarked convex lens (no optical track) and asked to estimate its focal length quickly, how would you do it? explain.

This problem has been solved! see the answera non-uniform fire escape ladder is 6.0m long whenextended to the icy alley below. it is held at the top by africtionless pivot, and there is neglibible frictional force fromthe icy surface at the bottom. the ladder weighs 250n, and it'scenter of gravity is 2.0m along the ladder from the bottom. amother and child of total weight 750n are on the ladder 1.5m fromthe pivot. the ladder makes an angle θ with the horizontal.find the magnitude and direction ofa) the force exerted by the icy alley on the ladderb) the force exerted by the ladder on the pivotc) do your answers in part a and b depend on the angle?

Select the word from the list that best fits the definition classification of most stars on the h-r diagram

To do work, this truck uses energy stored in chemical fuel and an electrical battery. how much total energy does this truck put out?