A lunar lander is making its descent to Moon Base I. Thelander descends slowly under the retro-thrust of its descentengine. The engine is cut off when the lander is 5.0{\rm m} above the surface and has a downward speedof 0.80 {\rm m/s} . With the engine off, the lander is in freefall.
What is the speed of the lander just before it touches thesurface? The acceleration due to gravity on the moon is 1.6\;{\rm m}/{\rm s}^{2}