CHAPTER NO 02 FORCE AND MOTION PRACTICE MCQS FROM NOTES SOLUTION PHYSICS INN-ABDULLAH

 

Section 2.1 — Scalars

Answer Key with Hints/Solutions (2.1 MCQs)

1. (b) Sol: Scalars are described solely by magnitude without direction.
2. (c) Sol: Mass is explicitly listed as a scalar example.
3. (b) Sol: Distance is total length of path travelled irrespective of direction.
4. (b) Sol: Temperature measures average kinetic energy of particles.
5. (b) Sol: Directionless quantities need only a single number and unit.
6. (b) Sol: Scalars obey ordinary rules of arithmetic.
7. (b) Sol: Scalar addition: .
8. (b) Sol: Speed is rate of distance without direction, unlike velocity.
9. (c) Sol: Total path length is .
10. (b) Sol: Energy capacity of  is scalar.
11. (b) Sol: Temperature is average kinetic energy measure.
12. (b) Sol:  without direction is speed.
13. (b) Sol: Speed = distance / time = .
14. (b) Sol: Mass amount is directly .
15. (c) Sol: .

   Section 2.2 — Vectors (Graphical Representation & Rectangular Components)

Answer Key with Hints/Solutions (2.2 MCQs)

1. (b) Sol: Vectors have magnitude and direction.
2. (b) Sol: Length of arrow indicates magnitude.
3. (b) Sol: Denoted by bold face or arrow head ().
4. (b) Sol: Rectangular components are along mutually perpendicular directions.
5. (b) Sol: A component is its effective value in a given direction.
6. (c) Sol: By head-to-tail rule, .
7. (a) Sol: Perpendicular components operate independently at right angles.
8. (b) Sol: At , , .
9. (b) Sol: Force with magnitude and direction is a vector.
10. (b) Sol: Change in position with direction is displacement vector.
11. (a) Sol: Direction specifies where the velocity vector is directed.
12. (b) Sol: An upward vector acting purely along y-axis has y-component equal to its full magnitude ().
13. (b) Sol: .
14. (b) Sol:  units.
15. (c) Sol: .

 

Section 2.3 — Product of Two Vectors

Answer Key with Hints/Solutions (2.3 MCQs)

1. (b) Sol: Scalar product yields a scalar quantity.
2. (b) Sol: Defined as .
3. (b) Sol: , making the scalar product zero.
4. (a) Sol: Commutative property states .
5. (c) Sol: .
6. (b) Sol: Defined as .
7. (a) Sol: For parallel vectors , and .
8. (b) Sol: Magnitude of cross product equals the area of the parallelogram formed by them.
9. (b) Sol: Reversing order changes direction, resulting in .
10. (a) Sol: Rearranging scalar product in component form gives .
11. (b) Sol: Work done is defined as the scalar product of force and displacement ().
12. (c) Sol: Torque  is a vector product application.
13. (a) Sol: .
14. (c) Sol: .
15. (c) Sol: .

 

Section 2.4 — Equations of Motion

Answer Key with Hints/Solutions (Equations of Motion MCQs)

1. (b) Sol: Equations of motion correlate velocity, position, and time.
2. (b) Sol: First equation relates final velocity with initial velocity and time (velocity-time relation).
3. (b) Sol: Second equation relates displacement, initial velocity, time, and acceleration (position-time relation).
4. (a) Sol: Third equation links velocity and displacement () without time.
5. (b) Sol: Valid exclusively for objects moving in a straight line with constant acceleration.
6. (b) Sol: Average velocity is used because acceleration makes velocity change over time.
7. (b) Sol: Vector quantities can be manipulated like scalars if direction does not change.
8. (b) Sol: Initial velocity is positive, and opposite vectors are assigned a negative sign.
9. (c) Sol: .
10. (b) Sol: .
11. (a) Sol: The problem specifies constant acceleration.
12. (b) Sol: The slope of line AB on a velocity-time graph represents acceleration.
13. (b) Sol: .
14. (b) Sol: .
15. (b) Sol: .

 

Section 2.5 — Motion Under Gravity

Answer Key with Hints/Solutions (Motion Under Gravity MCQs)

1. (b) Sol: Free fall under gravity is the familiar example of uniformly accelerated rectilinear motion.
2. (b) Sol: Galileo concluded all bodies fall freely in vacuum under acceleration 'g' with identical terminal impact velocities from equal heights.
3. (b) Sol: Average value of 'g' at Earth's surface is .
4. (b) Sol: 'g' is taken negative for bodies projected vertically upward against gravity.
5. (b) Sol: 'g' is positive for falling bodies with zero initial velocity.
6. (a) Sol: Gravitational acceleration is a constant constant independent of object mass in vacuum.
7. (b) Sol: At maximum height, upward velocity reduces to zero before reversing.
8. (b) Sol: Substituting  adapts kinematic equations for free fall.
9. (b) Sol: .
10. (b) Sol: Velocity increases uniformly due to constant acceleration .
11. (c) Sol: .
12. (c) Sol: .
13. (b) Sol: .
14. (b) Sol: .
15. (b) Sol: .

 

Section 2.6 — Projectile Motion

Answer Key with Hints/Solutions (Projectile Motion MCQs)

1. (b) Sol: Projectile motion is 2D motion under constant acceleration due to gravity.
2. (b) Sol: No horizontal force acts (ignoring air resistance), so .
3. (b) Sol: Maximum height formula is .
4. (b) Sol: Range is maximum when , giving .
5. (c) Sol: Vertical acceleration is constant and equals acceleration due to gravity ().
6. (b) Sol: Newton's first law dictates constant horizontal velocity since horizontal force is zero.
7. (b) Sol: Horizontal and vertical motions are completely independent of each other.
8. (b) Sol: Air resistance slows horizontal and vertical motion, causing a skewed trajectory with steeper descent.
9. (b) Sol: Complementary angles ( and ) produce the exact same horizontal range.
10. (c) Sol: At peak height, vertical velocity component becomes zero temporarily.
11. (c) Sol: .
12. (b) Sol: .
13. (b) Sol: .
14. (c) Sol: .
15. (b) Sol: .
16. (c) Sol: Time to max height is . ? Wait,  or .
17. (b) Sol: At , . .
18. (b) Sol: .
19. (b) Sol: .
20. (b) Sol: .

     Section 2.7 — Momentum, Impulse, and Conservation of Momentum

Answer Key with Hints/Solutions (2.7 MCQs)

1. (b) Sol: Newton termed the quality of motion of a moving object as quantity of motion.
2. (b) Sol: Linear momentum is defined as .
3. (a) Sol: SI unit is  or .
4. (b) Sol: An isolated system has no external agency exerting a force on it.
5. (b) Sol: It extends easily to systems with changing mass like burning rockets.
6. (c) Sol: Total linear momentum of an isolated system remains constant.
7. (b) Sol: Sand increases impact time, reducing the impact force.
8. (b) Sol: Padding increases collision time, reducing the peak force below fracture levels.
9. (b) Sol: Momentum scales directly with mass (), requiring more force to change.
10. (a) Sol: Impulse () handles varying impact forces conveniently.
11. (c) Sol: .
12. (b) Sol: Impulse .
13. (c) Sol:  (Magnitude is ).
14. (a) Sol: .
15. (c) Sol: .

 

Section 2.8 — Elastic and Inelastic Collisions

Answer Key with Hints/Solutions (2.8 MCQs)

1. (b) Sol: Inelastic collision is defined as one where system kinetic energy is not conserved.
2. (b) Sol: Total momentum and total energy are conserved in all types of collisions.
3. (b) Sol: In an ideal elastic collision, no kinetic energy is lost.
4. (a) Sol: Magnitude of relative velocity of approach equals magnitude of relative velocity of separation.
5. (b) Sol: Energy is lost partly due to friction, heat, and sound during molecular distortion.
6. (b) Sol: Equal mass elastic collision results in velocity exchange ().
7. (a) Sol: Light body bounces back with the same velocity while massive stationary body stays still.
8. (b) Sol: Massive body keeps its velocity while light body moves forward at roughly twice the incident velocity.
9. (b) Sol: Hard ball dropped on marble floor rebounding nearly to initial height is nearly elastic.
10. (b) Sol: Squash players use light ball bouncing off massive stationary walls.
11. (a) Sol: .
12. (d) Sol: .
13. (a) Sol: Equal masses result in complete velocity exchange: .
14. (c) Sol: Relative speed of approach equals relative speed of separation ().
15. (c) Sol: Light stationary body hit by massive body moves at approximately twice the incident speed ().

 

Section 2.09 — Inelastic Collision in One Dimension

Answer Key with Hints/Solutions (Inelastic Collisions MCQs)

1. (b) Sol: A perfectly inelastic collision occurs when colliding objects stick together to form a single mass.
2. (b) Sol: They move together with a common final velocity.
3. (a) Sol: Derived from momentum conservation: .
4. (b) Sol: Fraction of kinetic energy lost is .
5. (b) Sol: Kinetic energy is lost due to transformation into heat, sound, and deformation work.
6. (b) Sol: Final velocity is scaled down by the mass ratio factor .
7. (b) Sol: When , fraction lost  approaches  ( loss).
8. (b) Sol: A bullet embedding itself in wood is a classic perfectly inelastic collision.
9. (b) Sol: Energy is dissipated as sound and heat during impact.
10. (c) Sol: Combined mass .
11. (b) Sol: .
12. (b) Sol: .
13. (b) Sol: .
14. (c) Sol: .
15. (c) Sol: Fraction lost = .

 

Section 2.10 — Elastic Collision in Two Dimensions

Answer Key with Hints/Solutions (2.9 MCQs)

1. (b) Sol: In 2D collisions, bodies do not end up traveling along the same initial axis.
2. (c) Sol: Elastic collisions conserve both total linear momentum and total kinetic energy.
3. (b) Sol: Impulses send bodies off at angles  and  to the x-axis.
4. (a) Sol: Momentum conservation along x-axis is .
5. (a) Sol: Momentum is a vector quantity operating across a 2D plane requiring orthogonal resolution.
6. (b) Sol: Y-axis momentum before collision is zero, balanced by opposite vertical components after collision ().
7. (a) Sol: Kinetic energy is a scalar quantity, so vector component breakdown is unnecessary for energy formulas.
8. (b) Sol: Impulses generated between colliding bodies direct them off-axis.
9. (b) Sol: Conservation of both momentum and kinetic energy proves the collision is elastic.
10. (b) Sol: .
11. (c) Sol: .
12. (c) Sol: Momentum is conserved, so final x-momentum equals initial x-momentum ().
13. (b) Sol: , matching initial momentum.
14. (a) Sol: .
15. (c) Sol: Analysis reveals four unknown quantities: , , , and .

 

Section 2.11 — Inelastic Collision in Two Dimensions

Answer Key with Hints/Solutions (2.11 MCQs)

1. (b) Sol: Perfectly inelastic collision in 2D involves objects sticking together to form a single mass moving with a common velocity vector.
2. (b) Sol: Momentum conservation along x-axis equates initial x-momenta to combined final x-momentum component.
3. (b) Sol: Momentum conservation along y-axis equates initial y-momenta sum to combined final y-momentum component.
4. (a) Sol: Final direction angle  is obtained via  of total y-momentum components divided by total x-momentum components.
5. (a) Sol: Kinetic energy is a scalar quantity, so vector component breakdown is not required for energy calculations.
6. (b) Sol: Kinetic energy is not conserved and is lost as heat, sound, and deformation.
7. (b) Sol: A karate chop breaking bricks with horizontal/vertical motion components illustrates 2D inelastic behavior.
8. (b) Sol: Car crashes are inelastic in both horizontal and vertical directions with structural crumpling.
9. (a) Sol: Ball and bat collisions are inelastic because the ball compresses and converts energy to heat and sound.
10. (c) Sol: Combined mass .
11. (b) Sol: Initial momentum .
12. (b) Sol: Initial .
13. (b) Sol: Final .
14. (c) Sol: Energy loss .
15. (a) Sol: Squaring and adding orthogonal momentum equations yields the magnitude of the final velocity vector.

 

Section 2.12 — Rocket Propulsion

Answer Key with Hints/Solutions (Rocket Propulsion MCQs)

1. (b) Sol: Rockets move by expelling burning gas through engines at their rear.
2. (a) Sol: Rockets carry fuel in the form of liquid or solid hydrogen and oxygen.
3. (c) Sol: A typical rocket consumes about  of fuel.
4. (c) Sol: More than  of the launch mass consists of fuel only.
5. (b) Sol: They carry their own fuel and oxygen, allowing operation where no air is present.
6. (b) Sol: Acceleration increases as mass  decreases while thrust remains constant.
7. (a) Sol: Multi-stage linked rockets solve the heavy fuel mass problem.
8. (b) Sol: The rocket gains momentum equal and opposite to the expelled gases, pushing upward.
9. (a) Sol: Used stages are discarded, leaving others to continue at greater speeds.
10. (b) Sol: Thrust .
11. (b) Sol: .
12. (b) Sol: Change in momentum per second .
13. (b) Sol: .
14. (c) Sol: .
15. (c) Sol: Acceleration  is inversely proportional to mass , so halving mass doubles acceleration.