A toy helicopter takes off and moves 5 m up and then 2 m back down. What is the displacement of the helicopter?
A. 5 m
O B. 2 m down
O c. 3 m up
O D. 7 m

explanation:

v=uf/(u-f)

= 5.-10/(5+10) convex lens has negative focal length

in this image, you can see solar radiation going through ocean water.

no image, but probably absorption