50 unique MCQs on NDA Paper B Physics (Physical Properties of Matter, Motion, Force & Newton's Laws

NDA Exam (Paper B: General Knowledge) - Physics: Matter, Motion, Force & Newton's Laws Practice Test

Targeted 50 MCQ Practice Module focusing on: Physical Properties of Matter, Distance/Speed/Velocity, Acceleration & Equations of Motion, Force & Newton's Laws, and Momentum/Friction/Circular Motion.

Select your answers and click Submit Assessment Answers at the bottom to calculate your total score and review explanations.

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SECTION I: Physical Properties of Matter [Questions 1 to 10]

1. What is the SI unit of density?

kg/m² kg/m³ N/m² kg-m

Explanation: Density is mass per unit volume, so its SI unit is kilogram per cubic metre (kg/m³).

2. Elasticity is defined as the property of a material by virtue of which it:

Regains its original shape and size after the removal of a deforming force Flows continuously under any applied force Resists compression only Expands indefinitely when heated

Explanation: Elasticity is the ability of a body to return to its original shape and size once the deforming force is withdrawn.

3. Which state of matter has a definite volume but no definite shape?

Solid Liquid Gas Plasma

Explanation: A liquid has a fixed volume but takes the shape of the container it is poured into.

4. The property due to which the free surface of a liquid behaves like a stretched elastic membrane is called:

Viscosity Surface tension Capillarity Elasticity

Explanation: Surface tension arises from cohesive forces between liquid molecules, making the surface act like a stretched membrane.

5. A body that does not regain its original shape at all after the removal of a deforming force is called:

A perfectly elastic body A perfectly plastic body A rigid body A ductile body

Explanation: A perfectly plastic body shows no tendency to recover its original shape after deformation, e.g. putty or wet clay.

6. The SI unit of pressure is the:

Newton Joule Pascal Watt

Explanation: Pressure is force per unit area, and its SI unit is the Pascal (1 Pa = 1 N/m²).

7. The rise or fall of a liquid in a narrow tube due to surface tension is called:

Viscosity Capillarity Osmosis Diffusion

Explanation: Capillarity is the phenomenon of a liquid rising or falling in a narrow tube due to the combined effect of surface tension and adhesion/cohesion.

8. The property of a fluid by virtue of which it opposes the relative motion between its adjacent layers is called:

Surface tension Viscosity Elasticity Cohesion

Explanation: Viscosity is the internal friction of a fluid that resists relative motion between its layers.

9. Young's Modulus of Elasticity is associated with which type of strain?

Volumetric strain Shearing strain Longitudinal strain Lateral strain

Explanation: Young's Modulus is the ratio of longitudinal stress to longitudinal strain for a wire or rod stretched or compressed along its length.

10. As the temperature of a liquid increases, its viscosity generally:

Increases Decreases Remains constant Becomes zero

Explanation: Heating a liquid weakens the intermolecular cohesive forces, which reduces its viscosity.

SECTION II: Motion – Distance, Speed & Velocity [Questions 11 to 20]

11. A physical quantity that has both magnitude and direction is called a:

Scalar Vector Tensor Constant

Explanation: Vectors are quantities described completely only when both their magnitude and direction are specified, e.g. displacement, velocity, force.

12. The distance travelled by a moving body is a:

Vector quantity Scalar quantity Dimensionless quantity Complex quantity

Explanation: Distance has only magnitude and no specific direction, making it a scalar quantity, unlike displacement.

13. The SI unit of speed is:

km/hr m/s m/s² Newton

Explanation: Speed is distance travelled per unit time, and its SI unit is metre per second (m/s).

14. The average speed of a moving body is defined as:

Displacement divided by time Total distance travelled divided by total time taken Change in velocity divided by time Force divided by mass

Explanation: Average speed considers the total path length (distance) covered over the total time taken, regardless of direction.

15. A body moves along a complete circular path and returns exactly to its starting point. Its net displacement is:

Equal to the distance travelled Zero Maximum possible Negative

Explanation: Displacement is measured from the initial to the final position; since both coincide here, the net displacement is zero, even though the distance travelled is not.

16. If a body moves with constant (uniform) velocity, its acceleration is:

Increasing Decreasing Zero Infinite

Explanation: Acceleration is the rate of change of velocity; if velocity is constant, there is no change, so acceleration is zero.

17. Which instrument in a vehicle measures its instantaneous speed?

Odometer Speedometer Barometer Anemometer

Explanation: A speedometer shows the speed of the vehicle at a given instant of time.

18. A body is said to move with uniform velocity when it covers:

Unequal displacements in equal intervals of time Equal displacements in equal intervals of time, in the same direction Equal distances in unequal intervals of time Zero displacement in equal intervals of time

Explanation: Uniform velocity means both the speed and direction of motion remain unchanged, so equal displacements occur in equal time intervals along a straight line.

19. The total path length covered by a vehicle over its journey is recorded by which instrument?

Speedometer Odometer Tachometer Altimeter

Explanation: An odometer records the cumulative distance travelled by a vehicle.

20. Two cars move in the same direction with velocities 20 m/s and 15 m/s. Their relative velocity with respect to each other is:

35 m/s 5 m/s 300 m/s 15 m/s

Explanation: When two bodies move in the same direction, their relative velocity is the difference of their velocities: 20 − 15 = 5 m/s.

SECTION III: Motion – Acceleration & Equations of Motion [Questions 21 to 30]

21. The SI unit of acceleration is:

m/s m/s² N-s kg m/s

Explanation: Acceleration is the rate of change of velocity with time, so its SI unit is metre per second squared (m/s²).

22. The equation v = u + at, relating final velocity, initial velocity, acceleration and time, is known as the:

Second equation of motion Third equation of motion First equation of motion Law of inertia

Explanation: v = u + at is the first of the three standard kinematic equations of uniformly accelerated motion.

23. The equation s = ut + (1/2)at², used to find displacement, is known as the:

First equation of motion Second equation of motion Third equation of motion Newton's second law

Explanation: s = ut + (1/2)at² is the second equation of motion, giving displacement in terms of initial velocity, time and acceleration.

24. The equation v² = u² + 2as, which does not involve time, is known as the:

First equation of motion Second equation of motion Third equation of motion Impulse-momentum theorem

Explanation: v² = u² + 2as is the third equation of motion, relating velocities and displacement without reference to time.

25. The slope of a velocity-time graph represents:

Displacement Distance Acceleration Speed

Explanation: Since acceleration is the rate of change of velocity with time, it is given by the slope of the velocity-time graph.

26. The area enclosed under a velocity-time graph represents:

Acceleration Displacement Force Momentum

Explanation: The area under a velocity-time graph, between the curve and the time axis, gives the displacement of the body.

27. For a body starting from rest and moving with uniform acceleration, the distance covered is proportional to:

Time Square of time Square root of time Inverse of time

Explanation: With u = 0, s = (1/2)at², so distance covered is directly proportional to the square of the time elapsed.

28. When the velocity of a body decreases with time, the acceleration is called:

Positive acceleration Uniform velocity Retardation (negative acceleration) Terminal velocity

Explanation: A decrease in velocity with time is termed retardation or deceleration, which is simply negative acceleration.

29. A body falling freely under gravity, ignoring air resistance, has an acceleration equal to:

Zero g, directed downward, approximately 9.8 m/s² A value that keeps increasing indefinitely g, directed upward

Explanation: In free fall, the only force acting is gravity, giving the body a constant downward acceleration g, approximately 9.8 m/s².

30. The slope of a displacement-time graph at any point gives the body's:

Acceleration Velocity Force Momentum

Explanation: Velocity is the rate of change of displacement with time, so it is represented by the slope of the displacement-time graph.

SECTION IV: Force & Newton's Laws of Motion [Questions 31 to 40]

31. Newton's First Law of Motion is also known as the:

Law of Momentum Law of Inertia Law of Gravitation Law of Action-Reaction

Explanation: Newton's First Law states that a body continues in its state of rest or uniform motion unless acted upon by an external force, which is why it is called the Law of Inertia.

32. The SI unit of force is the:

Joule Watt Newton Pascal

Explanation: Force is defined as mass times acceleration, and its SI unit is the Newton (N).

33. The equation F = ma represents Newton's:

First Law Second Law Third Law Law of Gravitation

Explanation: Newton's Second Law states that force equals the rate of change of momentum, which for constant mass simplifies to F = ma.

34. "For every action, there is an equal and opposite reaction" is a statement of Newton's:

First Law Second Law Third Law Law of Inertia

Explanation: Newton's Third Law states that for every action force, there exists a reaction force of equal magnitude but opposite direction.

35. The inertia of a body is directly dependent upon its:

Velocity Mass Volume Shape

Explanation: Inertia is the tendency of a body to resist a change in its state of motion, and this tendency increases with the mass of the body.

36. One Newton is defined as the force required to produce an acceleration of:

1 m/s² in a body of mass 1 kg 1 m/s² in a body of mass 10 kg 10 m/s² in a body of mass 1 kg 1 cm/s² in a body of mass 1 g

Explanation: By definition, 1 Newton = 1 kg × 1 m/s², i.e., the force that gives a 1 kg mass an acceleration of 1 m/s².

37. The momentum of a body is defined as the product of its:

Mass and acceleration Mass and velocity Force and time Weight and height

Explanation: Momentum (p) is defined as p = mv, the product of a body's mass and its velocity.

38. The impulse of a force acting on a body is equal to the:

Mass multiplied by acceleration Change in momentum produced in the body Force multiplied by distance Mass multiplied by displacement

Explanation: Impulse = Force × time = Change in momentum, as derived directly from Newton's Second Law.

39. The Law of Conservation of Momentum states that the total momentum of a system remains constant, provided:

The bodies involved are in a vacuum No external force acts on the system All the bodies have equal mass All the bodies have equal velocities

Explanation: In the absence of any net external force, the total momentum of an isolated system before an event equals the total momentum after it.

40. Wearing a seatbelt in a moving car helps protect passengers during sudden braking, mainly due to the effect described by:

Newton's Third Law Newton's Second Law The Law of Inertia (Newton's First Law) The Law of Gravitation

Explanation: When a car stops suddenly, a passenger's body tends to continue moving forward due to inertia; the seatbelt provides the restraining force to prevent injury.

SECTION V: Momentum, Friction & Circular Motion [Questions 41 to 50]

41. Friction is a force that always acts:

In the direction of motion Opposite to the relative motion (or tendency of motion) between surfaces Perpendicular to the direction of motion Independent of the surfaces in contact

Explanation: Friction is a resistive force that opposes the relative sliding or the tendency of sliding between two surfaces in contact.

42. The friction that comes into play when a force is applied to a body at rest but the body still does not move is called:

Kinetic friction Rolling friction Static friction Fluid friction

Explanation: Static friction acts on a body at rest and adjusts itself up to a maximum limit to prevent the body from moving.

43. The friction acting on a body that is already sliding over another surface is called:

Static friction Kinetic (or sliding) friction Rolling friction Limiting friction only

Explanation: Once a body starts sliding, the opposing frictional force is called kinetic or sliding friction, which is generally less than the maximum static friction.

44. Rolling friction, compared to sliding friction between the same pair of surfaces, is generally:

Greater than sliding friction Exactly equal to sliding friction Much less than sliding friction Completely independent of sliding friction

Explanation: Rolling friction is considerably smaller than sliding friction, which is why wheels and ball bearings are used to reduce resistance to motion.

45. In uniform circular motion, the centripetal force acting on the body is always directed:

Away from the center of the circle Tangential to the circular path Towards the center of the circle In the same direction as the velocity

Explanation: Centripetal force is the net force directed towards the center of the circular path, which keeps the body moving along the curved track.

46. Centrifugal force, as experienced by an object in a rotating reference frame, is best described as a:

Real, externally applied force Pseudo (fictitious) force Gravitational force Frictional force

Explanation: Centrifugal force is not a real force in an inertial frame; it is a pseudo force that appears to act outward only when observed from a rotating (non-inertial) frame of reference.

47. The coefficient of friction between two surfaces mainly depends upon:

The area of contact between the surfaces The nature and roughness of the surfaces in contact The speed at which the body moves The color of the surfaces

Explanation: The coefficient of friction is a property of the pair of materials in contact and depends chiefly on the roughness/smoothness of their surfaces, not on the apparent contact area.

48. Lubricants such as oil and grease are used between moving machine parts primarily to:

Increase friction between the parts Reduce friction and wear between the parts Increase the weight of the machine Increase the operating temperature

Explanation: Lubricants form a thin film between moving surfaces, reducing direct contact and thereby lowering friction and wear.

49. When a stone tied to a string is whirled in a horizontal circle, the force acting on it towards the center of the circle is called:

Centrifugal force Gravitational force Centripetal force Frictional force

Explanation: The tension in the string provides the centripetal force that continuously pulls the stone towards the center, keeping it in circular motion.

50. According to the Law of Conservation of Momentum, in the absence of any external force, the total momentum of a system of colliding bodies before collision is:

Always greater than the total momentum after collision Always less than the total momentum after collision Equal to the total momentum after collision Always zero, regardless of the collision

Explanation: Momentum is conserved in any collision as long as no external force acts on the system, so total momentum before collision equals total momentum after collision.

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