Question 16
2 pts
Which of the following statements are true?
\sum vec(F)=mvec(a)
is only true for non-rotating objects. For rotating objects, you instead have to use the rotational analogue
\sum vec(f)=Ivec(\alpha )
.
An object is in static equilibrium if it is at rest, the net force on it is
vec(0)
, and the net torque on it about any axis is
vec(0)
.
Just as with moment of inertia, the components of the net torque on an object are axes-dependent.
Objects which are not constrained to rotate about some axis (i.e. unconstrained objects) can only spin about axes which pass through their center of mass.
While you can always compute
\sum vec(\tau )
on an object/system about any axis, it will only equal "I
vec(\alpha )
" if every point of the system has the same angular acceleration
vec(\alpha )
about that axis.