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Conservation of Angular Momentum

This category covers problems involving the conservation of angular momentum in isolated systems. Solve questions to see how angular momentum remains constant in different scenarios.

25 questions

A force F\=−2i^+5j^N acts at r\=4i^−3j^m. What is the magnitude of the torque about the origin?

τ = r×F = |i^j^k^4−30−250| = k^(4×5−(−3)×(−2)) = k^(20−6) = 14k^Nm. Magnitude = 14Nm. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 14 Nm. This satisfies dimensional consistency and physical conditions given, so option C is scientifically correct.

Ref: NCERT Class 11 Physics, Thermal Properties and Gravitation.

Three particles of masses 1kg, 2kg, and 3kg are located at (1,1), (2,3), and (4,2) respectively. What is the y-coordinat

Formula: Y = m1y1+m2y2+m3y3m1+m2+m3. Masses: 1,2,3kg; y-coordinates: 1,3,2. Y = (1×1)+(2×3)+(3×2)1+2+3 = 1+6+66 = 136≈2.17m. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 2.17 m. This satisfies dimensional consistency and physical conditions given, so option C is scientifically correct.

Ref: NCERT Class 11 Physics, Thermal Properties and Gravitation.

A solid sphere of mass 1kg and radius 0.8m has a kinetic energy of 12.8J. What is its angular speed?

I = 25MR2 = 25×1×(0.8)2 = 0.256kg m2. K = 12Iω2⇒12.8 = 12×0.256×ω2⇒25.6 = 0.256ω2⇒ω2 = 100⇒ω = 10rad/s. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 10 rad/s. This satisfies dimensional consistency and physical conditions given, so option B is scientifically correct.

Ref: NCERT Class 11 Physics, Thermal Properties and Gravitation.

Three particles of masses 2kg, 4kg, and 6kg are at (0,2), (3,0), and (1,4) respectively. What is the x-coordinate of the

Formula: X = m1x1+m2x2+m3x3m1+m2+m3. Masses: 2,4,6kg; x-coordinates: 0,3,1. X = (2×0)+(4×3)+(6×1)2+4+6 = 0+12+612 = 1812 = 1.5m. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 1.5 m. This satisfies dimensional consistency and physical conditions given, so option B is scientifically correct.

Ref: NCERT Class 11 Physics, Thermal Properties and Gravitation.

What determines the magnitude of torque on a rigid body?

The magnitude of torque (τ = rFsin⁡θ) depends on the force magnitude F and the perpendicular distance rsin⁡θ from the pivot to the line of action of the force. As per NCERT, applying relevant law/formula with correct units and sign convention leads to Force and perpendicular distance from the pivot. This satisfies dimensional consistency and physical conditions given, so option C is scientifically correct.

Ref: NCERT Class 11 Physics, Thermal Properties and Gravitation.

Two particles of masses 6kg and 4kg are at (2,3) and (8,7) respectively. What is the distance of their center of mass fr

X = (6×2)+(4×8)6+4 = 12+3210 = 4.4. Y = (6×3)+(4×7)6+4 = 18+2810 = 4.6. Distance = (4.4)2+(4.6)2 = 19.36+21.16 = 40.52≈6.36m. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 6.36 m. This satisfies dimensional consistency and physical conditions given, so option B is scientifically correct.

Ref: NCERT Class 11 Physics, Thermal Properties and Gravitation.

A solid cylinder of mass 4kg and radius 0.2m rolls without slipping with a linear speed of 2m/s. What is its angular vel

For rolling without slipping: v = ωr. v = 2m/s, r = 0.2m. ω = vr = 20.2 = 10rad/s. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 10 rad/s. This satisfies dimensional consistency and physical conditions given, so option B is scientifically correct.

Ref: NCERT Class 11 Physics, Thermal Properties and Gravitation.

A 2kg particle moves with velocity v\=−5i^−3j^m/s at r\=4i^m. What is the z-component of its angular momentum?

L = r×p = |i^j^k^400−5−30| = k^(4×(−3)−0×(−5)) = −12k^kg m2/s. Z-component = −12kg m2/s. As per NCERT, applying relevant law/formula with correct units and sign convention leads to -12 kg m²/s. This satisfies dimensional consistency and physical conditions given, so option B is scientifically correct.

Ref: NCERT Class 11 Physics, Thermal Properties and Gravitation.

A 3kg mass rotates in a circle of radius 0.7m with a speed of 4.2m/s. What is its angular momentum about the center?

L = mvr. m = 3kg, v = 4.2m/s, r = 0.7m. L = 3×4.2×0.7 = 8.82kg m2/s. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 8.82 kg m²/s. This satisfies dimensional consistency and physical conditions given, so option B is scientifically correct.

Ref: NCERT Class 11 Physics, Thermal Properties and Gravitation.

A 4kg particle moves with velocity v\=−2j^m/s at r\=5i^m. What is the magnitude of its angular momentum about the origin

L = r×p = |i^j^k^5000−20| = k^(5×(−2)−0×0) = −10k^kg m2/s. Magnitude = 10kg m2/s. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 10 kg m²/s. This satisfies dimensional consistency and physical conditions given, so option C is scientifically correct.

Ref: NCERT Class 11 Physics, Thermal Properties and Gravitation.