120 Important MCQs explores fundamental concepts in physics related to forces and motion, including gravity’s pull, friction’s resistance, acceleration’s changes in speed, and the utility of simple machines. Ideal for students learning Newtonian mechanics and everyday applications. Designed to test understanding through varied scenarios.
1. What is the primary force that keeps objects on Earth's surface?
✅ Correct Answer: b) Gravity
📝 Explanation:
Gravity is the attractive force between masses, pulling objects toward Earth's center with an acceleration of approximately 9.8 m/s².
2. According to Newton's first law, an object at rest will remain at rest unless acted upon by what?
✅ Correct Answer: b) An unbalanced force
📝 Explanation:
Newton's first law states that objects maintain their state of motion or rest due to inertia unless an external unbalanced force acts on them.
3. Friction is a force that acts in which direction relative to motion?
✅ Correct Answer: b) Opposite to the direction of motion
📝 Explanation:
Friction opposes relative motion between surfaces in contact, reducing speed and converting kinetic energy to heat.
4. What is the acceleration due to gravity on Earth, approximately?
✅ Correct Answer: b) 9.8 m/s²
📝 Explanation:
The standard value for gravitational acceleration (g) near Earth's surface is 9.8 m/s², used in free-fall calculations.
5. A simple machine that changes the direction of a force is a
✅ Correct Answer: b) Pulley
📝 Explanation:
A pulley redirects force, often used to lift loads by pulling downward, reducing the effort needed.
6. Newton's second law relates force, mass, and what?
✅ Correct Answer: b) Acceleration
📝 Explanation:
F = ma, where force equals mass times acceleration, showing how force causes changes in motion.
7. Static friction is greater than kinetic friction. What does static friction prevent?
✅ Correct Answer: b) Initiation of motion
📝 Explanation:
Static friction acts to prevent an object from starting to move, and is typically higher than kinetic friction once motion begins.
8. If an object falls freely, ignoring air resistance, its acceleration is constant at
✅ Correct Answer: c) 9.8 m/s²
📝 Explanation:
In free fall, gravity provides constant acceleration of 9.8 m/s² downward, regardless of mass.
9. A lever is a simple machine consisting of a
✅ Correct Answer: b) Rigid bar pivoting on a fulcrum
📝 Explanation:
Levers amplify force or distance by rotating around a fulcrum, classified into first, second, and third classes.
10. What unit is used to measure force in the SI system?
✅ Correct Answer: c) Newton
📝 Explanation:
One newton (N) is the force required to accelerate a 1 kg mass at 1 m/s².
11. Air resistance is a type of what force?
✅ Correct Answer: b) Frictional
📝 Explanation:
Air resistance, or drag, is a frictional force opposing motion through air, increasing with speed.
12. Acceleration is defined as the change in velocity per unit
✅ Correct Answer: c) Time
📝 Explanation:
Acceleration a = Δv / Δt, measuring rate of velocity change over time.
13. An inclined plane reduces the force needed to lift an object by increasing
✅ Correct Answer: b) The distance traveled
📝 Explanation:
Inclined planes trade effort for distance, making work easier by spreading force over a longer path.
14. Weight is the force due to
✅ Correct Answer: b) Gravity acting on mass
📝 Explanation:
Weight W = mg, where m is mass and g is gravitational acceleration.
15. Newton's third law states that for every action, there is an equal and opposite
✅ Correct Answer: c) Reaction
📝 Explanation:
Action-reaction pairs are equal in magnitude and opposite in direction, like propulsion in rockets.
16. Lubricants reduce friction by
✅ Correct Answer: b) Creating a layer of fluid between surfaces
📝 Explanation:
Lubricants form a thin film that minimizes direct contact, converting sliding friction to rolling or fluid friction.
17. If force doubles and mass remains the same, acceleration
✅ Correct Answer: c) Doubles
📝 Explanation:
From F = ma, acceleration is directly proportional to force when mass is constant.
18. A screw is a simple machine that combines an inclined plane with a
✅ Correct Answer: c) Cylinder
📝 Explanation:
A screw wraps an inclined plane around a cylinder, converting rotational motion to linear force.
19. Terminal velocity occurs when
✅ Correct Answer: b) Gravitational force equals drag
📝 Explanation:
At terminal velocity, net force is zero, so acceleration stops and speed remains constant.
20. The normal force is perpendicular to the surface and equals
✅ Correct Answer: b) Weight on a horizontal surface
📝 Explanation:
On a flat surface at rest, normal force balances weight to prevent sinking.
21. Deceleration is a negative form of
✅ Correct Answer: b) Acceleration
📝 Explanation:
Deceleration is acceleration in the opposite direction to motion, reducing speed.
22. In a pulley system with two supporting ropes, the mechanical advantage is
✅ Correct Answer: b) 2
📝 Explanation:
Mechanical advantage equals the number of supporting strands sharing the load.
23. Gravitational potential energy depends on mass, gravity, and
✅ Correct Answer: b) Height
📝 Explanation:
PE = mgh, where h is height above a reference point.
24. Rolling friction is less than sliding friction because
✅ Correct Answer: c) Wheels rotate
📝 Explanation:
Rolling converts sliding to rotation, reducing energy loss at contact points.
25. If velocity changes from 10 m/s to 30 m/s in 5 s, acceleration is
✅ Correct Answer: b) 4 m/s²
📝 Explanation:
a = (30 - 10)/5 = 4 m/s².
26. A first-class lever has the fulcrum between the effort and
✅ Correct Answer: a) Load
📝 Explanation:
Examples include seesaws, where fulcrum is in the middle.
27. Universal gravitation states that every mass attracts every other mass with a force proportional to
✅ Correct Answer: b) Product of masses and inverse square of distance
📝 Explanation:
F = G(m1 m2)/r², Newton's law of universal gravitation.
28. Coefficient of friction is a measure of
✅ Correct Answer: b) Frictional force relative to normal force
📝 Explanation:
μ = F_friction / F_normal, dimensionless value indicating friction intensity.
29. An object with zero acceleration has
✅ Correct Answer: d) Both a and c
📝 Explanation:
From Newton's second law, zero net force implies constant velocity (including rest).
30. A wheel and axle is a simple machine where the wheel has a
✅ Correct Answer: a) Larger radius than the axle
📝 Explanation:
Turning the larger wheel applies torque to the smaller axle, multiplying force.
31. On the Moon, gravity is about 1/6th of Earth's, so an object's weight would be
✅ Correct Answer: b) 1/6th as much
📝 Explanation:
Weight depends on local g; Moon's g is ~1.6 m/s² vs. Earth's 9.8 m/s².
32. Brakes on a car use friction to cause
✅ Correct Answer: c) Deceleration
📝 Explanation:
Brake pads create friction against wheels, opposing motion to slow the vehicle.
33. Average acceleration is total change in velocity divided by
✅ Correct Answer: c) Total time
📝 Explanation:
Formula: a_avg = Δv / Δt.
34. A second-class lever has the load between the fulcrum and
✅ Correct Answer: a) Effort
📝 Explanation:
Examples include wheelbarrows, providing mechanical advantage greater than 1.
35. Inertia is the tendency of an object to
✅ Correct Answer: b) Resist changes in motion
📝 Explanation:
Inertia, from Newton's first law, depends on mass; more mass means greater inertia.
36. Viscous friction occurs in
✅ Correct Answer: b) Fluids like air or water
📝 Explanation:
Viscosity causes resistance in fluids, proportional to speed differences in layers.
37. If a 2 kg object accelerates at 3 m/s², the net force is
✅ Correct Answer: c) 6 N
📝 Explanation:
F = ma = 2 * 3 = 6 N.
38. A wedge is used to
✅ Correct Answer: b) Split or separate objects
📝 Explanation:
Wedges convert force along their length to perpendicular separation force.
39. Escape velocity from Earth is about
✅ Correct Answer: b) 11.2 km/s
📝 Explanation:
Escape velocity is the speed needed to overcome Earth's gravity without further propulsion.
40. The angle of an inclined plane affects the component of gravity parallel to the plane, which is
✅ Correct Answer: a) mg sinθ
📝 Explanation:
Parallel component causes acceleration down the plane; θ is the angle with horizontal.
41. Centripetal force is directed toward the
✅ Correct Answer: b) Center of the circle
📝 Explanation:
It provides the acceleration for circular motion, F_c = mv²/r.
42. If mass doubles and acceleration halves, force
✅ Correct Answer: c) Stays the same
📝 Explanation:
F = ma; changes cancel out, keeping product constant.
43. A third-class lever has the effort between the fulcrum and
✅ Correct Answer: a) Load
📝 Explanation:
Examples include tweezers; mechanical advantage is less than 1.
44. Buoyant force is an upward force due to
✅ Correct Answer: b) Pressure difference in fluids
📝 Explanation:
Archimedes' principle: equals weight of displaced fluid.
45. Kinetic energy increases with the square of
✅ Correct Answer: b) Velocity
📝 Explanation:
KE = ½ mv², so doubling speed quadruples energy.
46. To minimize friction in machines, use
✅ Correct Answer: b) Bearings or rollers
📝 Explanation:
Bearings reduce contact by allowing rolling motion.
47. Instantaneous acceleration is the limit of average acceleration as time approaches
✅ Correct Answer: b) Zero
📝 Explanation:
It's the derivative of velocity with respect to time.
48. Mechanical advantage of a single fixed pulley is
✅ Correct Answer: a) 1
📝 Explanation:
It changes direction but not magnitude of force.
49. Tides are caused by gravitational pull of
✅ Correct Answer: b) Moon and Sun
📝 Explanation:
Differential gravity creates bulges in oceans.
50. Friction always
✅ Correct Answer: b) Opposes relative motion
📝 Explanation:
It dissipates energy as heat, slowing objects.
51. If distance is 100 m and time 10 s, average speed is 10 m/s; if accelerating from rest, average acceleration is
✅ Correct Answer: c) 2 m/s²
📝 Explanation:
v_avg = 10 m/s, a = v/t = 10/5? Wait, from s = ½ at², a = 2s/t² = 200/100 = 2 m/s².
52. A ramp with small angle has high
✅ Correct Answer: b) Mechanical advantage
📝 Explanation:
MA = 1/sinθ; smaller θ means larger MA.
53. Balanced forces result in
✅ Correct Answer: b) Zero net force
📝 Explanation:
Net force zero means no acceleration, constant velocity.
54. Parachutes increase air resistance to
✅ Correct Answer: c) Slow descent
📝 Explanation:
Larger area increases drag, balancing weight sooner.
55. Force of gravity between two objects decreases with
✅ Correct Answer: c) Increasing distance
📝 Explanation:
Inverse square law: force ∝ 1/r².
56. In uniform circular motion, acceleration is
✅ Correct Answer: b) Constant speed, changing direction
📝 Explanation:
Centripetal acceleration changes velocity direction.
57. A block on a rough surface needs more force to start moving than to keep moving due to
✅ Correct Answer: b) Static friction
📝 Explanation:
Static > kinetic friction.
58. Work done by friction is always
✅ Correct Answer: b) Negative
📝 Explanation:
Friction opposes displacement, so W = F·d cos180° = -Fd.
59. A movable pulley has mechanical advantage of
✅ Correct Answer: b) 2
📝 Explanation:
It halves the effort by moving with the load.
60. Apparent weight in an accelerating elevator going up feels
✅ Correct Answer: b) More
📝 Explanation:
Normal force = mg + ma for upward acceleration.
61. Vector quantity among these is
✅ Correct Answer: c) Acceleration
📝 Explanation:
Acceleration has magnitude and direction.
62. To accelerate a car, engine overcomes
✅ Correct Answer: b) Friction and air resistance
📝 Explanation:
These resistive forces require net force for acceleration.
63. Ideal mechanical advantage ignores
✅ Correct Answer: a) Friction
📝 Explanation:
IMA = input distance / output distance, assuming no energy loss.
64. Free fall assumes no
✅ Correct Answer: c) Air resistance
📝 Explanation:
All objects accelerate at g regardless of mass.
65. Hooke's law relates force to
✅ Correct Answer: a) Spring extension
📝 Explanation:
F = -kx, restoring force proportional to displacement.
66. If two masses are equal, the one with greater velocity has more
✅ Correct Answer: a) Momentum
📝 Explanation:
p = mv; velocity affects linear momentum.
67. Sand on icy roads increases friction by
✅ Correct Answer: b) Increasing surface roughness
📝 Explanation:
Rough particles provide better grip.
68. Equation for motion with constant acceleration: v = u +
✅ Correct Answer: a) at
📝 Explanation:
First kinematic equation: final velocity = initial + acceleration × time.
69. A gear system is a type of
✅ Correct Answer: b) Wheel and axle
📝 Explanation:
Gears are toothed wheels that transmit torque.
70. Microgravity in space feels like weightlessness because
✅ Correct Answer: b) Constant free fall
📝 Explanation:
Orbits create apparent zero-g as objects fall around Earth.
71. Drag force in fluids is proportional to
✅ Correct Answer: a) Square of velocity
📝 Explanation:
For high speeds, F_d ∝ v².
72. Net force on an object in equilibrium is
✅ Correct Answer: b) Zero
📝 Explanation:
Balanced forces mean no acceleration.
73. Efficiency of a simple machine is less than 100% due to
✅ Correct Answer: b) Friction and heat loss
📝 Explanation:
Some work input converts to non-useful energy.
74. Projectile motion combines horizontal
✅ Correct Answer: a) Constant velocity and vertical acceleration
📝 Explanation:
No horizontal force (ignore air), vertical g.
75. Tension in a rope pulling an object is a
✅ Correct Answer: b) Pulling force
📝 Explanation:
Tension acts along the rope, away from the object.
76. If a car accelerates at 5 m/s² with mass 1000 kg, engine force is
✅ Correct Answer: c) 5000 N
📝 Explanation:
F_net = ma = 1000 * 5 = 5000 N.
77. A block and tackle pulley system can have MA up to
✅ Correct Answer: b) Number of ropes
📝 Explanation:
Each rope segment supports part of the load.
78. Gravitational field strength g is
✅ Correct Answer: a) Force per unit mass
📝 Explanation:
g = F/m, measured in N/kg or m/s².
79. Slippery surfaces have low
✅ Correct Answer: a) Coefficient of friction
📝 Explanation:
Low μ means less resistance to motion.
80. Displacement-time graph slope gives
✅ Correct Answer: b) Velocity
📝 Explanation:
v = ds/dt.
81. A seesaw is a
✅ Correct Answer: a) First-class lever
📝 Explanation:
Fulcrum in middle, like scissors.
82. Coriolis force affects
✅ Correct Answer: b) Motion on rotating Earth
📝 Explanation:
Fictitious force deflecting winds and currents.
83. Power is work done per unit
✅ Correct Answer: c) Time
📝 Explanation:
P = W/t, rate of energy transfer.
84. In a hydraulic jack, force multiplication uses
✅ Correct Answer: a) Pascal's principle
📝 Explanation:
Pressure transmitted equally in fluids.
85. An object thrown upward reaches max height when velocity is
✅ Correct Answer: b) Zero
📝 Explanation:
Deceleration due to g stops upward motion.
86. Rubber soles on shoes increase friction via
✅ Correct Answer: b) High coefficient material
📝 Explanation:
Rubber grips surfaces better than smooth materials.
87. s = ut + ½ at² is equation for
✅ Correct Answer: b) Displacement
📝 Explanation:
Second kinematic equation.
88. Door knob is an example of
✅ Correct Answer: a) Lever
📝 Explanation:
Turning handle applies torque around hinge.
89. Weightlessness in orbit is due to
✅ Correct Answer: b) Free fall acceleration matching orbital
📝 Explanation:
Everything falls together toward Earth.
90. Stokes' law applies to drag on
✅ Correct Answer: a) Spheres in viscous fluids
📝 Explanation:
F_d = 6πηrv for low Reynolds number.
91. Impulse is change in
✅ Correct Answer: b) Momentum
📝 Explanation:
J = FΔt = Δp.
92. Actual mechanical advantage accounts for
✅ Correct Answer: b) Friction losses
📝 Explanation:
AMA = load/effort, less than IMA.
93. Horizontal component of velocity in projectile is
✅ Correct Answer: a) Constant
📝 Explanation:
No horizontal acceleration.
94. Thrust is a force from
✅ Correct Answer: b) Expelled mass, like rockets
📝 Explanation:
Action-reaction: gas backward, rocket forward.
95. If a = 0, then from v² = u² + 2as, v =
✅ Correct Answer: b) u
📝 Explanation:
Constant velocity, no change.
96. Nutcracker is a
✅ Correct Answer: a) First-class lever
📝 Explanation:
Fulcrum at one end, effort and load on other.
97. Black holes have gravity so strong that
✅ Correct Answer: b) Escape velocity exceeds light speed
📝 Explanation:
Event horizon where v_esc = c.
98. Fluid friction is measured by
✅ Correct Answer: a) Viscosity
📝 Explanation:
Viscosity quantifies internal resistance to flow.
99. Velocity-time graph area gives
✅ Correct Answer: b) Displacement
📝 Explanation:
∫v dt = s.
100. Bottle opener is a
✅ Correct Answer: a) Second-class lever
📝 Explanation:
Load (cap) between fulcrum and effort.
101. In Atwood's machine, acceleration depends on
✅ Correct Answer: b) Difference in masses
📝 Explanation:
a = (m1 - m2)g / (m1 + m2).
102. Conservation of energy in motion ignores
✅ Correct Answer: a) Friction
📝 Explanation:
Non-conservative forces like friction dissipate energy.
103. Skiing downhill, acceleration is g sinθ minus
✅ Correct Answer: a) Friction
📝 Explanation:
Net force parallel = mg sinθ - f.
104. Angular acceleration relates to torque by
✅ Correct Answer: a) τ = Iα
📝 Explanation:
Rotational analog of Newton's second law.
105. Ice has low friction because
✅ Correct Answer: a) Melted layer lubricates
📝 Explanation:
Pressure melts ice, creating water film.
106. If u = 0, s = 20 m, a = 10 m/s², time t =
✅ Correct Answer: b) 2 s
📝 Explanation:
s = ½ at² → t = √(2s/a) = √(40/10) = 2 s.
107. Ramp with θ = 30°, parallel gravity component is
✅ Correct Answer: a) mg/2
📝 Explanation:
sin30° = 1/2.
108. Simple machines multiply
✅ Correct Answer: b) Force or distance
📝 Explanation:
They make work easier but don't change total work.
109. Satellite in geostationary orbit has period of
✅ Correct Answer: a) 24 hours
📝 Explanation:
Matches Earth's rotation, appears fixed in sky.
110. Coefficient of static friction μ_s is typically
✅ Correct Answer: c) Greater than kinetic
📝 Explanation:
μ_s > μ_k for most surfaces.
111. Force diagram for object on table includes
✅ Correct Answer: a) Weight down, normal up
📝 Explanation:
Balanced vertically.
112. v² = u² + 2as, if v=0, u=10 m/s, a=-9.8, s=
✅ Correct Answer: a) 5 m
📝 Explanation:
0 = 100 + 2(-9.8)s → s = 100/(19.6) ≈ 5.1 m.
113. Fishing rod is a
✅ Correct Answer: a) Third-class lever
📝 Explanation:
Effort between fulcrum (hand) and load (fish).
114. Kepler's third law relates period squared to
✅ Correct Answer: b) Semi-major axis cubed
📝 Explanation:
T² ∝ a³ for orbits.
115. Ball bearings reduce friction by
✅ Correct Answer: b) Rolling
📝 Explanation:
Roll between surfaces, lower resistance.
116. Average velocity = total displacement /
✅ Correct Answer: b) Time
📝 Explanation:
v_avg = Δs / Δt.
117. Hydraulic systems use incompressible
✅ Correct Answer: b) Liquids
📝 Explanation:
Pressure change transmits force via area difference.
118. Object in uniform motion has
✅ Correct Answer: b) Zero acceleration
📝 Explanation:
Straight line, constant speed.
119. On a banked curve, no friction needed if speed satisfies
✅ Correct Answer: a) v = √(rg tanθ)
📝 Explanation:
Centripetal from horizontal gravity component.
120. Drag coefficient depends on
✅ Correct Answer: a) Shape
📝 Explanation:
Streamlined shapes have low Cd.
121. Work-energy theorem: net work = change in
✅ Correct Answer: b) Kinetic energy
📝 Explanation:
W_net = ΔKE.
122. A 100 N force on 20 kg mass gives a =
✅ Correct Answer: a) 5 m/s²
📝 Explanation:
a = F/m = 100/20 = 5 m/s².
123. Compound machine is combination of
✅ Correct Answer: b) Multiple simple machines
📝 Explanation:
Like bicycle with gears and chain.
124. Galileo showed all objects fall at same rate ignoring
✅ Correct Answer: b) Air resistance
📝 Explanation:
From Pisa leaning tower experiment.
