Physics · Motion In A Straight Line · NEET
The vertical axis (y-axis) shows position x, meaning how far the object is from the chosen origin, with a sign (+ or -) for direction. The horizontal axis (x-axis) shows time t. So the graph is NOT a picture of the road the object travels on. A point (t, x) simply says: at time t, the object is at position x. This is the first thing NEET expects you to be sure about before you read anything else.
A straight line means the position changes by equal amounts in equal time intervals, so the velocity is constant. This is called uniform motion. A steeper line means a larger velocity (the object covers more distance in the same time). A line that goes up to the right means motion in the positive direction; a line going down to the right means motion in the negative direction.
A horizontal line means the position x is not changing while time keeps increasing. So the object is at rest (stationary). Its velocity is zero because the slope is zero. Students often confuse this with 'no time passing' - time still moves, only the position stays the same.
If velocity is changing (the object is accelerating), the position does NOT change by equal amounts in equal times, so the graph bends into a curve. For uniform acceleration the x-t graph is a parabola. A curve that gets steeper means the object is speeding up; a curve that flattens means it is slowing down.
Yes. Position is measured from an origin, and one direction is chosen as positive and the opposite as negative. If the object is on the negative side of the origin, x is negative and the point lies below the time axis. This is normal in one-dimensional motion and is different from distance, which is never negative.
The displacement-time (x-t) graphs of two moving particles make angles of 30 degrees and 45 degrees with the time axis. The ratio of their respective velocities v1 : v2 is:
Try the real previous-year questions from this chapter — each with the answer and a full solution.
It is a graph that shows where an object is at every moment of time. Position x is on the vertical axis and time t is on the horizontal axis, so you can see how the object's location changes as time passes.
Velocity is the slope of the x-t graph. For a straight line, slope = (change in position)/(change in time) = (x2 - x1)/(t2 - t1). A steeper line means a larger velocity. This is covered in detail in the next concept, 'slope of position-time graph is velocity'.
A straight line represents uniform motion, meaning the object moves with constant velocity. The steeper the line, the greater the constant velocity.
A line parallel to the time axis (horizontal) has zero slope, so the object is at rest. Its position does not change even though time keeps increasing.
A curve tells you the velocity is changing, so the object is accelerating. For uniformly accelerated motion the x-t graph is a parabola. NEET often asks you to match an x-t graph shape to the type of motion (rest, uniform, or accelerated).
