UPSC Prelims 2001 Q115: Science & Technology – Physics
Which of the following distance - time graphs (x - t) represents one - dimensional uniform
motion?
- (a) I
- (b) II
- (c) III
- (d) IV
Answer: (d) IV
Explanation
Distance-time graph that shows one-dimensional uniform motion
| Shape of x-t graph | Type of motion |
|---|---|
| Straight line sloping up (constant slope) | Uniform motion — equal distances in equal times |
| Horizontal straight line | Body at rest |
| Curve getting steeper | Accelerated motion |
| Curve getting flatter | Decelerated motion |
The figure for this question is not available, and no published copy we could find shows it or confirms the answer. The answer below is the key held in our question bank and is not independently verified. The rule itself is certain: in uniform motion the distance-time graph is a straight, sloping line, whose slope is the velocity. The bank key marks graph IV.
Answer: (d) IV.
Why each option is right or wrong
- (a) Incorrect. The bank key does not mark graph I.
- (b) Incorrect. The bank key does not mark graph II.
- (c) Incorrect. The bank key does not mark graph III.
- (d) CORRECT. The bank key marks graph IV.
Key point
On a velocity-time graph, uniform motion is a horizontal line; on a distance-time graph it is a sloping straight line.
Remember
Uniform motion = straight inclined distance-time graph.
Common mistakes
- Choosing the horizontal line, which means rest on an x-t graph.
- Choosing a curve, which shows changing speed.
- Mixing up x-t (distance) and v-t (velocity) graphs.
Exam tip
x-t graph: straight slope = uniform; curve = accelerating; flat = at rest.
Sources
- NCERT Class IX — Science, chapter 'Motion' (graphical representation)
- NCERT Class XI — Physics Part I, chapter 'Motion in a Straight Line'