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#net force

9 public questions tagged with this topic.

Diamagnetism, Paramagnetism and Ferromagnetism

The absence of a net force on a magnetic dipole in a uniform field implies:

**Diamagnetism** exhibits small negative susceptibility χ ≈ -10⁻⁵ to -10⁻⁶, weakly repelled from stronger to weaker field regions, no permanent moment, induced moment opposite to B, present in all materials but dominated by other effects. Superconductor perfect diamagnet with χ = -1, complete field expulsion. In a uniform magnetic field, the forces on the dipole’s poles are equal in magnitude and opposite in direction, resulting in no net translational force. This occurs because the field strength does not vary, unlike in a non-uniform field where a gradient would produce a net force. Substitu

Ref: NCERT > Physics Book > Magnetism and Matter > Diamagnetism, Paramagnetism and Ferromagnetism

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Electric Dipole - Moment, Field and Torque

What allows an electric dipole to experience a net force in a non-uniform electric field but not in a uniform one?

**Dipole moment** governs torque and energy in external field. Axial field stronger than equatorial, torque maximum at θ = 90°, zero when aligned. Work done rotating dipole relates to ΔU = pE(1 - cosθ), explaining stable equilibrium at θ = 0°. In a non-uniform field, the field strength varies across the dipole, causing unequal forces on the positive and negative charges. This results in a net force, unlike in a uniform field where equal and opposite forces cancel out. Substituting values gives Field gradient, which matches expected magnitude for this electrostatic configuration, confirming Cou

Ref: NCERT > Physics Book > Electric Charges and Fields > Electric Dipole - Moment, Field and Torque

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Superposition Principle and Equilibrium of Charges

Three charges \( +3 \, \mu\text{C}, +3 \, \mu\text{C}, -6 \, \mu\text{C} \) are at the vertices of an equilateral triang

**Superposition principle** asserts net Coulomb force on charge equals vector sum of forces from each other charge independently, F_net = Σ F_i, where F_i = k q q_i/r_i² r̂_i. In equilateral triangle or square symmetry, components may cancel at centroid, producing equilibrium. F₁ = F₂ = 9 × 10⁹ × (3 × 6 × 10⁻¹²/(2)²) = 0.0405 N (attractive). Angle 60°. Net F = √(F₁² + F₂² + 2 F₁ F₂ cos 60°) = √(0.0405² + 0.0405² + 0.0016425) = 0.0702 N . Substituting values gives 0.07 N, which matches expected magnitude for this electrostatic configuration, confirming Coulomb's and Gauss's principles and charg

Ref: NCERT > Physics Book > Electric Charges and Fields > Superposition Principle and Equilibrium of Charges

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Superposition Principle and Equilibrium of Charges

Why does an electric dipole experience a torque but no net force when placed in a uniform electric field?

**Vector addition of forces** underlies multi-charge analysis. Each pair contributes independent Coulomb force, resultant obtained by resolving components along axes. Equilibrium occurs when vector sum vanishes, often at symmetric points where contributions balance. In a uniform field, the forces on the positive and negative charges of the dipole are equal in magnitude and opposite in direction, resulting in no net force. However, these forces act at different points, creating a torque that tends to align the dipole with the field. Substituting values gives Equal and opposite forces, which mat

Ref: NCERT > Physics Book > Electric Charges and Fields > Superposition Principle and Equilibrium of Charges

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Gravitational Effects and Applications

Three masses of 4kg each are at the vertices of an equilateral triangle with side 3m. What is the net force on one mass?

Force between two masses: F = Gm1m2r2 = 6.67×10−114×432 = 1.185×10−10N. Two forces act at 60°: FR = F2+F2+2F2cos⁡60∘. FR = (1.185×10−10)2(1+1+1) = 1.185×10−103. FR≈2.05×10−10N. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 2.2 × 10⁻¹⁰ N. This satisfies dimensional consistency and physical conditions given, so option C is scientifically correct.

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

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Escape Velocity and Bound Systems

Three masses of 12kg each form an equilateral triangle with side 9m. What is the net force on one mass? (G\=6.67×10−11N

Force between two masses: F = Gm2r2 = 6.67×10−1112×1292 = 1.185×10−10N. Two forces at 60°: FR = F2+F2+2F2cos⁡60∘. FR = (1.185×10−10)2(1+1+1) = 1.185×10−103. FR≈2.05×10−10N. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 2.1 × 10⁻¹⁰ N. This satisfies dimensional consistency and physical conditions given, so option C is scientifically correct.

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

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Work, Energy and Orbital Mechanics

Three masses of 15kg each form an equilateral triangle with side 10m. What is the net force on one mass? (G\=6.67×10−11N

Force between two masses: F = Gm2r2 = 6.67×10−1115×15102 = 1.50×10−10N. Two forces at 60°: FR = F2+F2+2F2cos⁡60∘. FR = (1.50×10−10)2(1+1+1) = 1.50×10−103. FR≈2.60×10−10N. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 2.6 × 10⁻¹⁰ N. This satisfies dimensional consistency and physical conditions given, so option B is scientifically correct.

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

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Gravitational Potential and Field

Three masses of 10kg each form an equilateral triangle with side 7m. What is the net force on one mass? (G\=6.67×10−11N

Force between two masses: F = Gm2r2 = 6.67×10−1110×1072 = 1.36×10−10N. Two forces at 60°: FR = F2+F2+2F2cos⁡60∘. FR = (1.36×10−10)2(1+1+1) = 1.36×10−103. FR≈2.36×10−10N. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 2.4 × 10⁻¹⁰ N. This satisfies dimensional consistency and physical conditions given, so option C is scientifically correct.

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

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