Chapter 4: Rotational Motion & Gravitation (Set-3)

Torque depends on:

A Force only
B Distance only
C Both force & perpendicular distance
D Mass distribution

Angular momentum of a system changes when:

A Internal torque acts
B No torque acts
C External torque acts
D Mass increases

A bicycle wheel maintains direction due to:

A Large KE
B Gravitational force
C Angular momentum
D Air resistance

A figure skater spins faster by:

A Extending arms
B Pulling arms in
C Stopping rotation
D Increasing friction

Angular momentum depends on:

A Position vector only
B Linear momentum only
C Both r and p
D Gravitational force

If torque is doubled and MoI constant, angular acceleration:

A Halves
B Doubles
C Triples
D Zero

Angular momentum of Earth around Sun is conserved because:

A Rotation is constant
B Sun’s gravity provides central force
C Mass is fixed
D Distance doesn’t change

Gyroscope resists tilting because of:

A Inertia
B Gravity
C Angular momentum
D Linear speed

Torque is zero if:

A Force is zero
B Distance = 0
C Force direction passes through pivot
D All above

Units of angular impulse:

A N·m
B kg·m/s
C N·m·s
D J

MoI increases when:

A Speed increases
B Mass moves farther from axis
C Temperature rises
D Axis removed

A thin hoop has MoI =

A 1/2 MR²
B 1/4 MR²
C MR²
D 2/3 MR²

The property resisting change in rotational motion is:

A Energy
B Momentum
C Moment of inertia
D Torque

MoI of a solid sphere about an axis through centre:

A 2/5 MR²
B 1/2 MR²
C MR²
D 3/4 MR²

Which body accelerates fastest down incline?

A Ring
B Disc
C Hollow sphere
D Solid sphere

Radius of gyration decreases when:

A MoI increases
B Mass concentrated near axis
C Radius increases
D Temperature decreases

Rotational KE does NOT depend on:

A MoI
B Shape
C Angular speed
D Linear velocity

For same mass, MoI is smallest for:

A Rod
B Ring
C Disc
D Point mass at centre

Parallel axis theorem applies when axis is:

A Perpendicular
B Rotating
C Parallel
D Tilted

Perpendicular axis theorem:

A Iₓ + Iᵧ = I_z
B Iₓ = Iᵧ + I_z
C I_z = IₓIᵧ
D I_z = 2Iₓ

Rotational Newton’s law:

A F = ma
B p = mv
C τ = Iα
D L = Iω

Unit of angular acceleration:

A m/s
B rad/s
C rad/s²
D m/s²

Rotational equilibrium requires:

A Net force = 0
B Net torque = 0
C KE = 0
D ω = constant

Disc and ring rolled same incline; disc reaches earlier because:

A Mass larger
B Disc smaller MoI
C Ring lighter
D Gravity more on disc

For pure rolling, acceleration relation:

A a = αr
B a = r/α
C a = α/r
D a = r²α

If torque constant & MoI decreases, α:

A Increases
B Decreases
C Zero
D No effect

Angular displacement measured in:

A Radians
B Degree per second
C m/s
D J

A wheel rotating with constant ω has:

A Zero α
B Positive α
C Negative α
D Variable α

Rolling object’s KE includes:

A Translational only
B Rotational only
C Translational + rotational
D None

Angular momentum conserved in:

A All systems
B Only isolated systems
C Bodies with zero mass
D Uniform motion

Central forces produce:

A Zero torque
B Maximum torque
C Constant torque
D Changing angular momentum

In central force field, path is always:

A Circular
B Linear
C Planar
D Three-dimensional

Non-central forces produce:

A No angular change
B Angular momentum change
C Zero energy
D No effect

Central force direction:

A Tangential
B Radial
C Perpendicular
D Parallel to velocity

Gravity is a:

A Non-central force
B Central force
C Tangential force
D Rotational force

Coulomb & gravitational force both follow:

A Linear law
B Inverse square law
C Constant law
D Quadratic law

F ∝ 1/r² implies:

A Long-range force
B Short-range force
C No conservation laws
D Constant force

If r → 0, gravitational force becomes:

A Zero
B Constant
C Infinite (ideal model)
D Negative

G is dimensionally:

A [M¹L³T⁻²]
B [M⁻¹L³T⁻²]
C [M⁻²L⁻²T²]
D [MLT]

The law F ∝ 1/r² suggests:

A Spherical symmetry
B Linear motion
C Variable mass
D Zero torque

g decreases with:

A Height
B Depth
C Both height & depth
D Neither

At infinite height, gravitational potential =

A Positive
B Negative
C Zero
D Maximum negative

Orbital velocity at height h:

A √(GM/R)
B √(GM/(R+h))
C GM/(R+h)²
D √(2GM/R)

Escape velocity from Earth:

A 5 km/s
B 7 km/s
C 11.2 km/s
D 15 km/s

g is maximum at:

A Equator
B Poles
C Centre
D Tropics

Total energy of satellite in circular orbit =

A KE
B PE
C −½ GMm/R
D +GMm/R

Work done by gravity during free fall:

A Zero
B Positive
C Negative
D Equal to KE decrease

A geostationary satellite stays above same point because:

A Fast orbit
B Period = 24 h
C Zero energy
D Perigee constant

Gravitational force between two objects depends on:

A Masses & radius
B Velocity
C Temperature
D Charge

Astronauts feel weightless because:

A No gravity
B Free fall inside spacecraft
C No mass
D Pressure low