A particle stays at rest as seen in a frame. We can conclude that
(a) the frame is inertial
(b) resultant force on the particle is zero
(c) the frame may be inertial but the resultant force on the particle is zero
(d) the frame may be noninertial but there is a nonzero resultant force.
Share with your friends
Call
(c) the frame may be inertial but the resultant force on the particle is zero
(d) the frame may be noninertial but there is a nonzero resultant force.
Explanation:
(a) is incorrect because if the particle and the non-inertial frame both are moving with same acceleration, the particle will be seen at rest from this frame. So we cannot conclude that the frame is inertial. (b) is also not correct. Suppose as viewed from an inertial frame a force F produces an acceleration a in a particle. If this particle be seen from a non-inertial frame that too is moving with same acceleration in the same direction, it will seem to be at rest. But the force on the particle is not zero. (c) and (d) are possible conditions.