Physics · Oscillations · NEET
No. Displacement is the signed straight-line gap from the mean position, so it can be positive or negative and it returns to zero every time the body crosses the centre. Distance is the total path length, which only grows. In one full oscillation the net displacement is zero, but the distance covered is 4A (four times the amplitude).
The mean position is the reference point (the centre of the to-and-fro motion). Displacement is measured from this point, so when the particle is exactly at the centre its distance from the reference is zero. At this point speed is maximum, not displacement.
The maximum displacement is the amplitude A. It happens at the two extreme (turning) points where the particle stops for an instant before moving back. So displacement ranges from -A to +A.
Yes. We pick one side of the mean position as positive and the other side as negative. When the particle is on the negative side, its displacement is negative. That is why displacement is a signed quantity, not just a size.
Not always. Displacement means the change in any physical quantity that measures the state of the system. For a swinging pendulum it can be the angle from the vertical, and for a vibrating gas it can be a pressure change. In basic NEET problems it is usually the straight-line distance y from the mean position.
The displacement of a particle executing simple harmonic motion is y = A0 + A sin(wt) + B cos(wt). The amplitude of its oscillation is
Try the real previous-year questions from this chapter — each with the answer and a full solution.
It is how far and in which direction the particle is from its centre (mean) position at a given moment, given as a signed value that keeps changing with time.
A common form is y = A sin(wt + phi), where A is the amplitude, w is the angular frequency, t is time, and phi is the phase constant. This gives the displacement at any instant t.
Amplitude is the maximum possible displacement from the mean position. Displacement varies between -A and +A, while amplitude A is a fixed number for a given oscillation.
Displacement is maximum (equal to A) at the two extreme turning points and zero at the mean position in the middle.
Displacement is the instantaneous signed distance from the centre and it keeps changing. Amplitude is the fixed maximum value that this displacement can reach.
