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.
