Angular momentum of a rotating rigid body depends on:
A Torque only
B Radius only
C Moment of inertia & angular velocity
D Linear speed only
L = Iω.
A larger lever arm produces:
A Smaller torque
B Larger torque
C Zero torque
D Constant torque
Torque = rF.
Angular momentum is conserved when:
A External torque = 0
B Internal torque = 0
C Applied force constant
D Speed constant
Only external torque affects L.
Unit of torque is same as unit of:
A Energy
B Angular momentum
C Work
D Pressure
Torque & work both have units N·m.
A rod pivoted at one end is easier to rotate if force applied:
A Near pivot
B Beyond pivot
C At the free end
D At midpoint
Larger r → larger torque.
Doubling angular velocity doubles:
A Angular momentum only
B MoI only
C Torque
D Both torque & MoI
L = Iω.
Angular momentum direction is:
A Opposite velocity
B Along torque
C Perpendicular to plane of rotation
D Same as linear momentum
Right-hand rule.
Gyroscopic effect stabilizes:
A Cars
B Satellites
C Bicycles
D All of these
Angular momentum provides stability.
A torque always changes:
A Angular velocity
B Linear velocity
C Radius
D MoI
Torque → α = dω/dt.
If angular momentum is constant and MoI increases, ω:
A Increases
B Decreases
C Remains same
D Becomes zero
L = Iω → ω ∝ 1/I.
MoI of uniform disc about central axis:
A MR²
B 1/2 MR²
C 2/3 MR²
D 1/4 MR²
Standard formula.
For ring rolling, total KE =
A Translational only
B Rotational only
C Translational + rotational
D Zero
Rolling motion = both.
Hollow sphere has higher MoI than solid sphere because:
A More mass
B More radius
C Mass farther from axis
D Shape difference only
MoI ∝ r².
Least MoI for a rod is about:
A One end
B Centre
C Diagonal axis
D Any axis
Shortest r → minimum inertia.
The quantity kg·m² measures:
A Torque
B Force
C Moment of inertia
D Momentum
SI unit of MoI.
Parallel axis theorem adds term:
A ML
B ML²
C MD
D Md²
I = Icm + Md².
MoI determines body’s:
A Temperature
B Mass
C Energy
D Rotational inertia
Resistance to rotational change.
Rotational KE does not depend on:
A MoI
B Angular velocity
C Mass
D Linear speed
KE_rot = ½ Iω².
Radius of gyration k represents:
A Mass of body
B Distance at which mass can be concentrated
C Rotational speed
D Axis tilt
k = √(I/M).
MoI of thin rod about end is:
A ML²
B 1/12 ML²
C 1/3 ML²
D 2ML²
Known value using parallel axis theorem.
Rotational work =
A Fd
B τθ
C Iω
D Lω
Equivalent to W = Fd.
Rotational power =
A τω
B τθ
C Iα
D Iω²
P = τω.
Pure rolling occurs when:
A v > rω
B v < rω
C v = rω
D α = v/r
No slipping condition.
In rolling motion, velocity at top of wheel =
A Zero
B v
C 2v
D v/2
Translational + rotational velocity.
Net torque on a body is zero; then:
A ω = 0
B α = 0
C L = 0
D KE = 0
Zero torque → zero angular acceleration.
Rotational kinetic energy increases if:
A MoI increases (ω constant)
B ω increases
C τ decreases
D v decreases
KE ∝ ω².
A wheel slows down due to:
A Zero MoI
B Positive torque
C Negative torque
D Increase in mass
Opposing torque reduces ω.
Angular displacement measured in:
A Radians
B Joules
C Newton
D m/s
Fundamental rotational quantity.
Rotational inertia increases when:
A Mass shifted outward
B Mass shifted inward
C Speed increases
D Axis removed
MoI increases with radius².
A body in rotational equilibrium has:
A Angular velocity = 0
B Net torque = 0
C MoI = constant
D g = constant
No angular acceleration.
Central forces always point toward:
A Tangent
B Axis
C Perpendicular direction
D Centre
Direction is radial.
A central force produces:
A No torque
B Maximum torque
C Negative torque
D Outward torque
r × F = 0 when F is radial.
Non-central forces change:
A Linear velocity
B Angular momentum
C Radius
D Mass
They exert torque.
Motion under central force lies in:
A 3D surface
B Any random path
C A plane
D Helical path
Angular momentum constant.
Gravitational force is:
A Non-central
B Central
C Opposing
D Purely tangential
Acts along joining line of masses.
If distance halves, gravitational force becomes:
A Double
B Half
C Four times
D One-fourth
F ∝ 1/r².
Value of G is:
A Same everywhere
B Maximum at poles
C Zero at equator
D Depends on mass
Universal constant.
Inverse square law applies to:
A Nuclear force
B Gravitational force
C Strong force
D Magnetic dipole only
F ∝ 1/r².
Gravitational force reduces with height because:
A r increases
B m decreases
C G decreases
D Time increases
Force ∝ 1/r².
Unit of gravitational constant G:
A N/kg
B m/s²
C N·m²/kg²
D kg·m/s
Derived from Newton’s law.
g is minimum at:
A Poles
B Equator
C Moon
D Centre of Earth
Due to rotation + equatorial bulge.
A body weighs less at equator because:
A Earth flat
B Earth rotates
C Sun pulls downward
D Mass reduces
Centrifugal force effective.
Orbital speed depends on:
A Satellite mass
B Planet’s mass & orbital radius
C Sunlight
D Shape of satellite
v = √(GM/R).
Escape velocity independent of:
A Planet mass
B Object mass
C Planet radius
D Gravitational constant
v_e = √(2GM/R).
A satellite in free fall feels:
A Maximum weight
B No weight
C Double weight
D Zero force
Free fall → weightlessness.
Gravitational potential energy (−GMm/r) is:
A Always zero
B Always positive
C Always negative
D Always maximum
Defined zero at infinity.
Kepler’s 3rd law states:
A T² ∝ r²
B T ∝ r³
C T² ∝ r³
D T³ ∝ r
Orbital period relation.
Total energy of orbiting satellite =
A KE
B PE
C KE + PE (negative)
D Zero
Bound orbits have negative total energy.
Gravitational force between two bodies is zero at:
A Infinite separation
B Poles
C Equator
D Earth’s centre
F → 0 as r → ∞.
Earth revolves around Sun because:
A No force
B Sun pushes Earth
C Gravity supplies centripetal force
D Earth rotates on axis
Gravity provides inward force.