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The Questions With Explanation is Given Below
Q1. ______ of a body due to which it opposes its state of rest or uniform motion is called
a) Momentum
b) Inertia
c) Torque
d) Weight
Answer: b) Inertia
Explanation: Inertia is the property of a body that resists changes to its state of rest or uniform motion. This is a fundamental concept in Newton’s First Law of Motion, often called the Law of Inertia. A body will remain at rest or in uniform motion unless acted upon by an external force, and inertia quantifies this resistance.
Q2. Which law of motion is also called law of inertia?
a) 1st law
b) 2nd law
c) 3rd law
d) 4th law
Answer: a) 1st law
Explanation: Newton’s First Law of Motion states that a body remains in its state of rest or uniform motion unless acted upon by an external force. This is also known as the Law of Inertia because it describes the tendency of a body to resist changes in its motion, which is the definition of inertia.
Q3. The inertia of an object is the quantitative measure of its
a) Volume
b) Density
c) Mass
d) Temperature
Answer: c) Mass
Explanation: Inertia is directly related to the mass of an object. The greater the mass, the greater the inertia, meaning the object is more resistant to changes in its motion. Mass is the quantitative measure of inertia, as seen in Newton’s Second Law (F = ma), where mass determines how much force is needed to accelerate an object.
Q4. Momentum depends upon
a) Velocity of the body
b) Mass of the body
c) Both mass and
velocity of the body
d) None
Answer: c) Both mass and velocity of the body
Explanation: Momentum (p) is defined as the product of an object’s mass (m) and its velocity (v): p = m v. Therefore, momentum depends on both mass and velocity. If either increases, the momentum increases proportionally.
Q5. The trajectory (or path) of a projectile is
a) Straight line
b) Parabola
c) Hyperbola
d) Circle
Answer: b) Parabola
Explanation: A projectile, when launched at an angle (not 0° or 90°), follows a parabolic trajectory due to the combined effects of its initial velocity and the downward acceleration due to gravity. The horizontal component of velocity remains constant (ignoring air resistance), while the vertical component changes due to gravity, resulting in a parabolic path.
Q6. A football player will throw a football at a maximum distance if the angle of projection is
a) 30°
b) 45°
c) 60°
d) 90°
Answer: b) 45°
Explanation: The range of a projectile is given by R = (v² sin 2θ)/g, where v is the initial velocity, θ is the angle of projection, and g is the acceleration due to gravity. The range is maximized when sin 2θ = 1, which occurs at 2θ = 90°, or θ = 45°. Thus, a football travels the maximum horizontal distance when thrown at 45°.
Q7. Motion of projectile is
a) One dimensional
b) Two dimensional
c) Three dimensional
d)
Four dimensional
Answer: b) Two dimensional
Explanation: Projectile motion occurs in two dimensions: horizontal (x-axis) and vertical (y-axis). The horizontal motion is uniform (constant velocity, assuming no air resistance), while the vertical motion is uniformly accelerated due to gravity. There is no motion in the third dimension (z-axis) unless specified otherwise, making it two-dimensional.
Q8. During projectile motion, the horizontal component of velocity
a) Changes with time
b) Becomes zero
c) Remains constant
d)
Increases with time
Answer: c) Remains constant
Explanation: In projectile motion (ignoring air resistance), the horizontal component of velocity (v_x = v cos θ) remains constant because there is no horizontal acceleration. Gravity acts only in the vertical direction, affecting the vertical component of velocity, but not the horizontal one.
Q9. The range of projectile is same for angles of projection
a) 30° and 45°
b) 45° and 60°
c) 50° and 45°
d) 30° and
60°
Answer: d) 30° and 60°
Explanation: The range of a projectile is given by R = (v² sin 2θ)/g. The sine function has the property that sin(180° - x) = sin x, so sin 2θ = sin (180° - 2θ). Thus, angles θ and 90° - θ give the same range. Here, 30° and 60° are complementary (30° + 60° = 90°), so their ranges are equal.
Q10. If both components of a vector are negative, then resultant lies in
a) 1st quadrant
b) 2nd quadrant
c) 3rd quadrant
d) 4th
quadrant
Answer: c) 3rd quadrant
Explanation: In a Cartesian coordinate system, a vector with both components negative (x < 0, y < 0) lies in the 3rd quadrant. The quadrants are defined as: 1st (x > 0, y > 0), 2nd (x < 0, y > 0), 3rd (x < 0, y < 0), 4th (x > 0, y < 0). Since both x and y are negative, the vector is in the 3rd quadrant.
Q11. In which quadrant the two rectangular components of a vector have same sign?
a) 3rd
b) 2nd
c) both 1st and 3rd
d) 4th
Answer: c) both 1st and 3rd
Explanation: The rectangular components of a vector are its x and y components. They have the same sign when both are positive or both are negative: 1st quadrant (x > 0, y > 0, both positive), 3rd quadrant (x < 0, y < 0, both negative). In the 2nd (x < 0, y > 0) and 4th (x > 0, y < 0) quadrants, the signs differ. Thus, the answer is 1st and 3rd quadrants.
Q12. If the x-component of a vector is positive and y-component is negative, then resultant vector lies in what quadrant?
a) 1st quadrant
b) 2nd quadrant
c) 3rd quadrant
d) 4th
quadrant
Answer: d) 4th quadrant
Explanation: If the x-component is positive (x > 0) and the y-component is negative (y < 0), the vector lies in the 4th quadrant, where x > 0 and y < 0, according to the quadrant definitions.
Q13. The resultant of two forces 30 N and 40 N acting at an angle of 90° with each other is
a) 30 N
b) 40 N
c) 60 N
d) 70 N
Answer: None of the options are correct; the correct answer should be 50 N.
Explanation: For two forces at 90°, the resultant is given by R = √(F₁² + F₂²). Here, F₁ = 30 N, F₂ = 40 N: R = √(30² + 40²) = √(900 + 1600) = √2500 = 50 N. However, 50 N is not an option. The closest option, 60 N, might suggest a typo in the angle. If the angle were 60°: R = √(30² + 40² + 2(30)(40) cos 60°) = √(900 + 1600 + 1200) = √3700 ≈ 60.8 N, which is close to 60 N. Based on the given question (90°), the correct resultant is 50 N, indicating an error in the options.
Q14. If A + B = B + A, this shows that addition of vectors is
a) Associative
b) Commutative
c) Additive
d) Additive
inverse
Answer: b) Commutative
Explanation: The property A + B = B + A shows that the order of addition does not affect the result, which is the commutative property of vector addition.
Q15. The angle between rectangular components of vector is
a) 45°
b) 60°
c) 90°
d) 180°
Answer: c) 90°
Explanation: The rectangular components of a vector are its x and y components (in 2D), which are along the x-axis and y-axis, respectively. These axes are perpendicular, so the angle between the components is 90°.
Q16. Dot product of two non-zero vectors is zero, when angle between them is
a) 0
b) 30
c) 45
d) 90
Answer: d) 90
Explanation: The dot product of two vectors A · B = |A| |B| cos θ. If the dot product is zero and the vectors are non-zero, then cos θ = 0, which occurs when θ = 90°.
Q17. The scalar product of two vectors is maximum when they are
a) Parallel
b) Perpendicular
c) Anti-parallel
Answer: a) Parallel
Explanation: The scalar (dot) product A · B = |A| |B| cos θ is maximum when cos θ = 1, which occurs at θ = 0°, meaning the vectors are parallel.
Q18. The direction of torque can be found by
a) Head to tail rule
b) Right hand rule
c) Left hand rule
d)
Fleming rule
Answer: b) Right hand rule
Explanation: The direction of torque is determined using the right hand rule: curl the fingers of your right hand in the direction of rotation caused by the force, and your thumb points in the direction of the torque vector.
Q19. The magnitude of a vector can never be
a) Positive
b) Negative
c) Zero
Answer: b) Negative
Explanation: The magnitude of a vector is always a non-negative scalar (it can be zero or positive). It represents the length of the vector, which cannot be negative.
Q20. The work done is said to be negative when force and displacement are
a) Parallel
b) Anti-parallel
c) Perpendicular
d) None
Answer: b) Anti-parallel
Explanation: Work done is W = F · d = F d cos θ. Work is negative when cos θ < 0, which occurs when θ is between 90° and 270°. The maximum negative work occurs at θ = 180°, when the force and displacement are anti-parallel (opposite directions).
Q21. Work has the same dimension as that of
a) Torque
b) Angular momentum
c) Linear momentum
d) Power
Answer: a) Torque
Explanation: Work is W = F · d, with dimensions [W] = [F][d] = (M L T⁻²)(L) = M L² T⁻². Torque is Ï„ = F · r, with the same dimensions: [M L² T⁻²]. Angular momentum (M L² T⁻¹), linear momentum (M L T⁻¹), and power (M L² T⁻³) have different dimensions.
Q22. If the mass of a moving object is doubled, its K.E becomes
a) 2 times
b) 4 times
c) 5 times
d) 16 times
Answer: None of the options are correct; the correct answer should be 2 times.
Explanation: Kinetic energy is K.E. = (1/2) m v². If the mass m is doubled (and velocity v remains constant), the new kinetic energy is: K.E._new = (1/2) (2m) v² = 2 [(1/2) m v²] = 2 × K.E._old. The correct answer is 2 times, but the options start at 4 times, suggesting a possible error in the question or options.
Q23. Work done on the body equals to
a) Change in its K.E always
b) Change in its K.E and change in its
P.E
c) Change in its P.E always
d) Neither change in K.E nor
change in P.E
Answer: a) Change in its K.E always (in the context of net work)
Explanation: According to the work-energy theorem, the net work done on an object equals the change in its kinetic energy: W_net = ΔK.E. However, if potential energy changes are involved (e.g., in a conservative field), the total mechanical energy (K.E. + P.E.) must be considered. The word “always” in option a) is misleading in a general context, but in the absence of potential energy changes, a) is correct. In a broader context, b) would be more accurate, but based on typical MCQ intent, a) is likely intended.
Q24. Work done by the force of friction is when car is moving along level ground
a) Always positive
b) Positive only for small frictional force
c)
Always negative
d) Positive only for large frictional force
Answer: c) Always negative
Explanation: Friction acts opposite to the direction of motion. For a car moving on a level ground, the displacement is in the direction of motion, but the frictional force is opposite. Thus, θ = 180°, and work done by friction is: W = F d cos 180° = - F d. The work done by friction is always negative in this scenario.
Q25. 1 revolution
a) 67°
b) 90°
c) 180°
d) 360°
Answer: d) 360°
Explanation: One revolution corresponds to a full circle, which is 360°.
Q26. One radian is equal to
a) 47.3°
b) 53°
c) 87.3°
d) 60°
Answer: None of the options are exactly correct; the correct answer should be 57.3°. The closest is b) 53°.
Explanation: 1 radian is 180/Ï€ ≈ 57.295°. None of the options match exactly, but 53° is the closest. This suggests a possible error in the options.
Q27. The rate of change of angular displacement is called
a) Angular displacement
b) Angular acceleration
c) Angular
velocity
d) Torque
Answer: c) Angular velocity
Explanation: Angular velocity (ω) is defined as the rate of change of angular displacement (θ) with respect to time: ω = dθ/dt.
Q28. Revolution/minute is the unit for
a) Angular displacement
b) Angular acceleration
c) Angular
velocity
d) Time
Answer: c) Angular velocity
Explanation: Revolution per minute (RPM) is a unit of angular velocity, as it measures the number of revolutions (angular displacement) per unit time.
Q29. Time rate of change of angular velocity is called
a) Angular momentum
b) Angular displacement
c) Angular
acceleration
d) None of these
Answer: c) Angular acceleration
Explanation: Angular acceleration (α) is the rate of change of angular velocity (ω) with respect to time: α = dω/dt.
Q30. When a body moves in a circle of radius ‘r’ with linear speed ‘v’, its centripetal force is
a) mv/r²
b) mv/r
c) mv²/r
d) mv²/r²
Answer: c) mv²/r
Explanation: The centripetal force required to keep a body of mass m moving in a circle of radius r with speed v is: F_c = (m v²)/r.
Q31. The angular acceleration of a body is directed
a) Away from the center of the circle
b) Along the radius towards
center
c) Along the tangent to the circle
d) Along the axis of
rotation with angular velocity in parallel or opposite
Answer: d) Along the axis of rotation with angular velocity in parallel or opposite
Explanation: Angular acceleration (α) is a vector quantity directed along the axis of rotation, parallel or opposite to the angular velocity vector, depending on whether the rotation is speeding up or slowing down.
Q32. The magnitude of the centripetal force on a mass m moving with angular speed ω in a circle of radius r is
a) m r² ω
b) m r² ω²
c) m r ω
d) m r ω²
Answer: d) m r ω²
Explanation: Centripetal force is F_c = (m v²)/r. Since v = ω r, we substitute: F_c = (m (ω r)²)/r = (m ω² r²)/r = m r ω².
Q33. Moment of inertia is measured in
a) kg m²
b) kg m
c) N s
d) rad/s
Answer: a) kg m²
Explanation: The moment of inertia (I) has dimensions of mass times distance squared: [I] = M L², so the SI unit is kg m².
Q34. The circumference subtends an angle
a) Radian
b) 2Ï€ radian
c) π/2 radian
d) π radian
Answer: b) 2Ï€ radian
Explanation: The circumference of a circle corresponds to one full revolution, which is 2Ï€ radians (since 360° = 2Ï€ radians).
Q35. When a body is whirled in a horizontal circle by means of a string, the centripetal force is supplied by
a) Mass of body
b) Velocity of body
c) Tension in the
string
d) None
Answer: c) Tension in the string
Explanation: The centripetal force required for circular motion is provided by the tension in the string, which acts toward the center of the circle.
Q36. Unit of angular velocity in SI unit is
a) rad/s
b) m/s
c) degrees
d) Revolution/s
Answer: a) rad/s
Explanation: The SI unit of angular velocity is radians per second (rad/s).
Q37. The minimum velocity necessary to put a satellite into orbit is
a) 7.1 km s⁻¹
b) 7.3 km s⁻¹
c) 7.9 km s⁻¹
d) 8.9 km s⁻¹
Answer: c) 7.9 km s⁻¹
Explanation: The orbital velocity for a satellite in low Earth orbit is approximately 7.9 km/s, derived from v = √(GM/r), where G is the gravitational constant, M is the mass of Earth, and r is the radius of the orbit (close to Earth’s radius for low orbit).
Q38. A particle is moving in a circle with constant speed. The direction of centripetal force will be
a) Along the tangent
b) Along radius away from center
c) Along
radius towards center
d) Changing with motion
Answer: c) Along radius towards center
Explanation: Centripetal force always acts toward the center of the circular path to keep the particle in circular motion.
Q39. The area under the curve of force-displacement graph is equal to
a) Displacement
b) Work
c) Power
d) Energy
Answer: b) Work
Explanation: The area under a force-displacement graph represents the work done, as W = ∫ F dx.
Q40. Work done will be maximum if the angle between the force F and displacement d is
a) 45°
b) 90°
c) 180°
d) 0°
Answer: d) 0°
Explanation: Work is W = F d cos θ. Work is maximum when cos θ = 1, which occurs at θ = 0°, meaning the force and displacement are in the same direction.
Q41. A field will be conservative when work is done
a) By centripetal force is zero
b) By a frictional force is
negative
c) By force perpendicular to the displacement is zero
d)
In a closed path is zero
Answer: d) In a closed path is zero
Explanation: A field is conservative if the work done by the field in a closed path is zero. This is a defining property of conservative forces like gravity.
Q42. A body covering equal displacement in equal interval of time possesses
a) Variable velocity
b) Uniform acceleration
c) Uniform
velocity
d) None of above
Answer: c) Uniform velocity
Explanation: If a body covers equal displacement in equal intervals of time, its velocity is constant (uniform velocity).
Q43. Instantaneous and average velocities become equal when body
a) Has acceleration
b) Has uniform velocity
c) Has variable
velocity
d) Moves in a circle
Answer: b) Has uniform velocity
Explanation: Instantaneous velocity is the velocity at a specific moment, while average velocity is the total displacement divided by total time. They are equal when the velocity is constant (uniform), as there is no acceleration to cause variation.
Q44. When the velocity-time graph is a straight line parallel to time axis then
a) Acceleration is const
b) Acceleration is variable
c)
Acceleration is zero
d) Velocity is zero
Answer: c) Acceleration is zero
Explanation: A velocity-time graph that is a straight line parallel to the time axis indicates that velocity is constant (not changing with time). Since acceleration is the rate of change of velocity (a = dv/dt), if velocity is constant, acceleration is zero.
Q45. The slope of the velocity-time graph is
a) Acceleration
b) Distance
c) Force
d) Momentum
Answer: a) Acceleration
Explanation: The slope of a velocity-time graph is the change in velocity per unit time, which is the definition of acceleration: a = Δv/Δt.
Q46. The area between the velocity-time graph and the time axis is numerically equal to
a) Velocity
b) Distance
c) Time
d) Acceleration
Answer: b) Distance
Explanation: The area under a velocity-time graph represents the displacement (or distance, if motion is in one direction). This is because displacement = velocity × time, and the area under the curve is the integral of velocity with respect to time.
Q47. What is the shape of velocity-time graph for constant acceleration?
a) Straight line
b) Parabola
c) Inclined curve
d)
Declined curve
Answer: a) Straight line
Explanation: For constant acceleration, velocity changes linearly with time (v = u + at). On a velocity-time graph, this relationship plots as a straight line with a constant slope (where the slope is the acceleration).
Q48. Change in momentum is called
a) Force
b) Impulse
c) Acceleration
d) Torque
Answer: b) Impulse
Explanation: Impulse is defined as the change in momentum of an object. It is given by Impulse = Δp = F Δt, where F is the force and Δt is the time interval over which the force acts.
Q49. The time rate of change of momentum is called
a) Force
b) Impulse
c) Acceleration
d) Torque
Answer: a) Force
Explanation: According to Newton’s Second Law, the rate of change of momentum is equal to the net force acting on an object: F = dp/dt. Since p = m v, if mass is constant, this becomes F = m a.
Q50. A body covering equal displacement in equal interval of time possesses
a) Variable velocity
b) Uniform acceleration
c) Uniform
velocity
d) None of above
Answer: c) Uniform velocity
Explanation: If a body covers equal displacement in equal intervals of time, its velocity is constant (uniform velocity), as there is no change in the rate of displacement over time.
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