B the force of static friction always has a direction

b. The force of static friction always has a direction that is…
A. opposite to the direction of the object’s velocity
B. opposite to the sum of all other external forces (components parallel to surface) on the object
c. Let F
N
= magnitude of normal force from the surface of contact. The force of static friction has a magnitude
that is…
F
N
03. Kinetic Friction:
a. The force of kinetic friction always has a direction that is…
b. The force of kinetic friction always has a direction that is… c. Let F
N
= magnitude of normal force from the surface of contact. The force of kinetic friction has a magnitude
that is…
A. always ½ µ
k
· F
N
B. always µ
k
·
C. any strength from zero to µ
k
· F
N
as needed to oppose the sum of other external forces (parallel to the surface)
F
N