circle most appropiate choice
1a. Which of the following forces is NOT a conservativeforce?
a. friction force
b. spring force
c. gravitational force
d. none of the above
1b. In which circumstance is the force of frictionbetween two surfaces at its maximum magnitude?
(Note: subscripts s and k specify the static and dynamicconditions, respectively.)
a. When friction angle satises (Φ < Φs)
b. When friction angle satises (Φ = Φs)
c. When friction angle satises (Φ = Φk)
d. None of the above
1c. Which of the following labels is WRONG?
a. 10e-6 : micro
b. 10e-9 : nano
c. 10e-12 : atto
d. 10e-15 : femto
1d. In curvilinear kinematics, when using the normal andtangential components to express the particle acceleration, thenormal acceleration is always _________________.
a. positive
b. negative
c. pointing toward the center of curvature
d. choices a and c
1e. Which one of the following equations are WRONG withrespect to cartesian unit vectors i, j, k, along x, y, and z axes,respectively? (Note: (X) indicates the cross product of twovectors)
a. i X j = k
b. k X j = -i
c. k X i = -j
d. j X j = 0
