NEET Physics: Motion in a plane Practice Questions
12 free multiple-choice questions on Motion in a plane (Kinematics) for NEET Physics, each with the correct answer and a step-by-step explanation. Attempt a question, then reveal the solution to check your reasoning.
Practice thousands more NEET questions in the app →Q1. A particle moves along the x-axis. Its position changes from x=5 m to x=15 m. What is the magnitude of the displacement?
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Correct answer: D — 10 m
Displacement is the change in position, calculated as final position minus initial position. Displacement = 15 m - 5 m = 10 m.
Q2. A body is moving with a constant speed of 10 m/s in a straight line. What is its acceleration?
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Correct answer: A — Zero
Acceleration is the rate of change of velocity. Since the speed is constant and the path is straight, the velocity is constant. If velocity is constant, acceleration is zero.
Q3. A stone is thrown vertically upwards. Which statement correctly describes its velocity at the highest point of its trajectory?
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Correct answer: C — The velocity is zero and directed downwards.
At the highest point of the trajectory, the particle momentarily stops before changing direction. Therefore, its instantaneous velocity is zero, and the acceleration (due to gravity) is directed downwards.
Q4. Two objects, A and B, are moving in a plane. If their velocities are always perpendicular to each other, what can be said about the magnitude of their resultant velocity?
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Correct answer: C — The resultant velocity is the magnitude of the vector sum, calculated using the Pythagorean theorem.
When two velocities are perpendicular, the magnitude of the resultant velocity is found by adding the squares of the individual velocities and taking the square root, which is the Pythagorean theorem (vector addition).
Q5. A car is moving due East at a constant speed of 20 m/s. If the car starts moving due North at a constant speed of 10 m/s, what is the magnitude of the resultant velocity?
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Correct answer: C — √50 m/s
Since the velocities are perpendicular (East and North), the resultant velocity is found using the Pythagorean theorem: vᵣₑₛᵤₗₜₐₙₜ = √((20)² + (10)²) = √(400 + 100) = √500 m/s.
Q6. What is the physical significance of displacement in motion?
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Correct answer: C — The shortest straight-line distance between the initial and final positions
Displacement is the shortest straight-line distance between the initial and final positions of an object, and it is a vector quantity.
Q7. A body moves along the positive x-axis. If its position changes from x=10 m to x=25 m, what is the magnitude of the displacement?
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Correct answer: C — 15 m
Displacement is the change in position. Displacement = Final position - Initial position = 25 m - 10 m = 15 m. Since the motion is along a straight line (x-axis), the magnitude of displacement is 15 m.
Q8. If an object has a velocity of 5 m/s purely in the positive x-direction, what is its velocity component in the y-direction?
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Correct answer: A — 0 m/s
If the velocity is purely in the positive x-direction, the velocity component in the y-direction must be zero.
Q9. A particle moves from point P(2, 3) to point Q(5, 7) in the xy-plane. What is the magnitude of the displacement vector?
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Correct answer: C — 4
The displacement vector vec(PQ) is calculated as (5-2)î + (7-3)ĵ = 3î + 4ĵ. The magnitude is √(3² + 4²) = √(9 + 16) = √25 = 5.
Q10. If the velocity of a body is constant and its direction changes, what does it imply about the acceleration of the body?
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Correct answer: C — The acceleration is non-zero and directed perpendicular to the velocity.
If velocity is constant, the acceleration must be zero (Newton's First Law). However, if the *direction* changes while the magnitude remains constant, the acceleration must be non-zero and directed perpendicular to the velocity (centripetal acceleration).
Q11. An object moving in a straight line has a constant velocity. What can be said about its acceleration?
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Correct answer: B — The acceleration is zero
If velocity is constant (constant speed and direction), the acceleration must be zero.
Q12. A vehicle moves along a straight line. Its velocity is given by v(t) = 2t + 1. What is the displacement covered between t=0 s and t=3 s?
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Correct answer: A — 9 m
Assuming the initial position x(0)=0, then x(t) = ∫ v(t) dt = t² + C. If x(0)=0, then x(t)=t². At t=3 s, displacement is 3² = 9 m.
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