A 4 kg block with a 1 kg block stacked on top initially slides at 2 m/s on a rough, horizontal
surface. The blocks continue to move as a unit with no sliding between the two. The blocks come to rest 1 m
away.

15. How much work did kinetic friction from the surface below do on the 4 kg block during this process?
a) -2 J
b) -6 J
c) -10 J
d) -14 J
e) -18 J

16. How much work did static friction from the 1 kg block above do on the 4 kg block during this process?
a) +2 J
b) +6 J
c) +10 J
d) +14 J
e) +18 J

17. What is the coefficient of kinetic friction between the 4 kg block and the surface below?
a) 0.35
b) 0.30
c) 0.25
d) 0.20
e) 0.15

Expert

Up of elements with the same number of valence electrons. vertical column in the periodic table of elements such as alkali metals or halogens. a horizontal row of elements in the periodic table. this is a characteristic of the elements in the periodic table that shows a pattern. it may increase or decrease across or down the table. periodic trend these are the highly reactive elements located in group 1 of the periodic table. these elements have one electron in their outer energy level which makes them highly reactive with water and halogens. these are the reactive elements located in group 2 of the periodic table. these elements have two electrons in their outer energy level which makes them reactive with water and halogens. alkaline earth metals these are the group 3 or d-block elements. these dense metals with high boiling points can have different oxidation states and all are solid at room temperature with the exception of mercury. transition metals this is the highly reactive family of elements with 7 valence electrons. this is an element with full valence shell, very unreactive. this is a group of elements with few valence electrons that conducts heat and electricity. one of a class of elements having properties intermediate to metals and nonmetals. this is a type of element that has many valence electrons, not a conductor.