Motion in a Straight LineNEET MCQs with solutions
Motion in a Straight Line covers kinematics — displacement, velocity, acceleration, equations of motion, free fall and motion graphs. NEET tests numerical problems using v = u + at, s = ut + ½at² and v² = u² + 2as, and graph interpretation (v-t, s-t, a-t). Speed and accuracy in applying equations is essential.
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- 11 Physics
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Practise 24 questions
Tap an option to check it. Questions from every NCERT topic in this chapter, from easy to hard.
Q1Mixed Revision
A particle moves 30 m east and then 40 m west along a straight line. Its displacement and distance travelled are respectively:
Not quite — the answer is C.
Distance = total path = 30 + 40 = 70 m. Displacement = 30 − 40 = −10 m, i.e., 10 m west (east positive). Option B fails: direction of displacement is west, not east.
Q2Mixed Revision
A car accelerates uniformly from rest at 2 m/s². The distance covered in the first 5 s is:
Not quite — the answer is B.
Using s = ½at² with u = 0: s = ½ × 2 × 25 = 25 m. Option A (20 m) arises from using s = at² without the ½ factor — a common error.
Q3Kinematic Equations for Uniform Acceleration
A car moving at 20 m/s applies brakes and decelerates uniformly at 4 m/s². How long does it take to come to rest?
Not quite — the answer is C.
v = u + at: 0 = 20 + (−4)t → t = 5 s. Option B (4 s) traps students who divide 20 by 5 instead of 4. Option D (6 s) has no valid computational source from this data set.
Q4Kinematic Equations for Uniform Acceleration
Which kinematic equation directly relates final velocity, initial velocity, acceleration and time, without involving displacement?
Not quite — the answer is A.
v = u + at contains only v, u, a, t — no displacement term. Option C eliminates time instead. Option B contains all variables. Option D contains displacement implicitly via average velocity.
Q5Relative Motion
The relative velocity of particle A with respect to particle B is given by:
Not quite — the answer is B.
By definition, v_AB = v_A − v_B. Option C is v_BA, equal in magnitude but opposite in sign. Option A and D ignore vector subtraction entirely.
Q6Relative Motion
Two cars move in the same direction with speeds of 20 m/s and 12 m/s. The speed of the faster car relative to the slower car is:
Not quite — the answer is C.
Same direction: relative speed = 20 − 12 = 8 m/s. Option D (32) traps students who add speeds. Option A (4) has no physical basis here.
Q7Acceleration
Acceleration is defined as the:
Not quite — the answer is C.
Acceleration = dv/dt. It is a vector quantity directed along the change in velocity, not necessarily along velocity itself. Option A defines velocity (ds/dt), Option B omits direction.
Q8Acceleration
The SI unit of acceleration is:
Not quite — the answer is B.
Acceleration = Δv/Δt = (m/s)/s = m/s². Option A is the unit of velocity. Option D (cm/s²) is the CGS unit, not SI. Option C is a valid unit but not the standard SI unit.
Q9Introduction & Position, Path Length and Displacement
A reference point from which the position of a particle is measured is called:
Not quite — the answer is C.
Origin is the fixed reference point; position is the coordinate of the particle measured from the origin along the chosen axis. Displacement and path length are derived quantities, not reference points.
Q10Introduction & Position, Path Length and Displacement
Which of the following is true for distance but NOT for displacement?
Not quite — the answer is C.
Distance depends on the actual path followed; displacement depends only on initial and final positions. Both are in metres and both can be zero, so options A and B cannot distinguish them.
Q11Velocity-Time Graphs
The slope of a velocity-time graph represents:
Not quite — the answer is C.
Slope of v-t graph = dv/dt = acceleration by definition. Students must not confuse: slope of x-t gives velocity, while slope of v-t gives acceleration — a high-frequency NEET answer-swap trap.
Q12Velocity-Time Graphs
The area under a velocity-time graph represents:
Not quite — the answer is B.
Area under v-t graph = ∫v dt = displacement. If the graph dips below the time axis, that area is negative displacement. Students who ignore sign below the axis compute distance, not displacement.
604 more questions on this chapter are waiting in the app
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Get RankUp on Google PlayQ13Average Velocity and Average Speed
A car travels 120 km in 2 hours. What is its average speed?
Not quite — the answer is C.
Average speed = total distance / total time = 120 / 2 = 60 km/h. It is always a non-negative scalar; displacement is not involved.
Q14Average Velocity and Average Speed
A particle moves 30 m east in 5 s and then 20 m east in 5 s. Its average velocity is:
Not quite — the answer is A.
Both legs are in the same direction so total displacement = 50 m east. Average velocity = 50 / 10 = 5 m/s east. Option C (2.5) wrongly halves the displacement before dividing.
Q15Grand Test
A car starts from rest and accelerates uniformly at 4 m/s². What is the distance covered in the 5th second of its motion?
Not quite — the answer is A.
Using sₙ = u + a(2n−1)/2: s₅ = 0 + 4×(9)/2 = 18 m. Option B (20 m) arises from using s=½at² for n=5 (total distance, not nth second). The nth second formula gives displacement in that specific second only.
Q16Grand Test
Which of the following is NOT a characteristic of uniform motion in a straight line?
Not quite — the answer is B.
In uniform motion, acceleration is zero, not constant and non-zero. Option A, C, D are all true for uniform motion. Non-zero constant acceleration defines uniformly accelerated motion, not uniform motion.
Q17Instantaneous Velocity and Speed
Instantaneous velocity of a particle is defined as the:
Not quite — the answer is B.
Instantaneous velocity = lim(Δt→0) Δx/Δt. As the time interval shrinks to zero, average velocity converges to velocity at that instant. Option A defines average velocity, not instantaneous velocity.
Q18Instantaneous Velocity and Speed
A particle moves along a straight line. At a particular instant its instantaneous velocity is −6 m/s, taking rightward as positive. Which of the following is correct?
Not quite — the answer is C.
Negative velocity means motion opposite to the positive direction, i.e., leftward. Instantaneous speed = |−6| = 6 m/s, which is always non-negative. Option D is wrong because speed can never be negative.
Q19Position-Time Graph
A horizontal position-time graph indicates that the particle is:
Not quite — the answer is B.
A horizontal line means position does not change with time, so the particle is stationary. Students often confuse a horizontal x-t line with a horizontal v-t line, which would indicate constant velocity.
Q20Position-Time Graph
The slope of a position-time graph represents:
Not quite — the answer is A.
Slope of x-t graph = dx/dt, which is instantaneous velocity by definition. Slope gives velocity (with sign), not speed; students who choose speed ignore the directional information carried by the sign.
Q21Freely Falling Bodies
A body is dropped from rest from a height. Which physical quantity remains constant throughout its fall (neglect air resistance)?
Not quite — the answer is C.
In free fall, g ≈ 9.8 m/s² acts constantly downward throughout the entire fall. Velocity and speed increase uniformly with time; displacement increases as t². Only acceleration remains unchanged.
Q22Freely Falling Bodies
A stone is dropped from rest. Taking g = 10 m/s², its speed after 3 s is:
Not quite — the answer is B.
v = u + gt = 0 + 10×3 = 30 m/s. Option A (20) traps students who use t = 2 s or forget to multiply correctly. Speed equals magnitude of velocity here since motion is in one direction.
Q23Introduction & Position, Path Length and Displacement
A body completes one full circle and returns to its starting point. Which of the following is correct?
Not quite — the answer is A.
Final position equals initial position, so displacement = 0. The body has traversed the full circumference, so distance = 2πr, which is non-zero. Confusing path length with displacement is the classic trap.
Q24Introduction & Position, Path Length and Displacement
Which of the following statements are correct? I. Position depends on the choice of origin. II. Position is a vector quantity. III. Distance can be negative. IV. Displacement may be zero after motion.
Not quite — the answer is D.
Statements I, II and IV are correct per NCERT. Distance is always non-negative (total path length), so Statement III is false. Displacement can be zero when a body returns to its starting point.
ELITE question · AIR under 50 level
This chapter has 206 ELITE questions for students aiming at the very top. They are only in the app.
Unlock ELITE questions in the appKey Kinematics Equations
Quick revision: most questions in this chapter test these facts.
| Equation | Key Fact |
|---|---|
| v = u + at | Final velocity; use when displacement is not given |
| s = ut + ½at² | Displacement; use when final velocity is not given |
| v² = u² + 2as | Velocity-displacement; use when time is not given |
| Free fall | a = g = 9.8 m/s² (downward); u = 0 if dropped |
| Relative velocity | v_AB = v_A − v_B (same direction); v_A + v_B (opposite) |
| v-t graph | Slope = acceleration; area under curve = displacement |
What the app covers in this chapter
628 questions in total, each with a detailed explanation.
| Mixed Revision | 79 |
| Kinematic Equations for Uniform Acceleration | 78 |
| Relative Motion | 61 |
| Acceleration | 60 |
| Introduction & Position, Path Length and Displacement | 59 |
| Velocity-Time Graphs | 59 |
| Average Velocity and Average Speed | 57 |
| Grand Test | 57 |
| Instantaneous Velocity and Speed | 40 |
| Position-Time Graph | 40 |
| Freely Falling Bodies | 38 |
Questions students ask
Is Motion in a Straight Line important for NEET?
Yes — kinematics is fundamental. Numerical problems on equations of motion and graph-based questions appear every year.
Which topics should I revise first?
Master all three equations of motion with sign conventions, free-fall problems, relative velocity and interpreting v-t and s-t graphs (slope and area).
How many questions from this chapter are on RankUp?
The RankUp app has 628 questions on Motion in a Straight Line, including 206 ELITE questions. Every question has a detailed explanation.
