Two blocks rest on a horizontal frictionless surface as shown. The surface between the top and bottom blocks is roughened so that there is no slipping between the two blocks. A 30-N force is applied to the bottom block as suggested in the figure.
10. What is the acceleration of the "two block" system?
A) 1 m/s²
B) 2 m/s²
C) 3 m/s²
D) 6 m/s²
E) 15 m/s²
11. What is the force of static friction between the top and bottom blocks?
A) zero newtons
B) 10 N
C) 20 N
D) 25 N
E) 30 N
12. What is the minimum coefficient of static friction necessary to keep the top block from slipping on the bottom block?
A) 0.05
B) 0.10
C) 0.20
D) 0.30
E) 0.40