NEET Physics: conservative and non-conservative forces Practice Questions

Correct answer: C — Air resistance

Air resistance and friction are non-conservative forces because the work they do depends on the path taken between the objects.

Correct answer: C — Elastic force (Spring force)

Elastic forces, such as the force exerted by a spring, are conservative forces because the work done depends only on the extension/compression, not the path taken. Friction and air resistance are non-conservative.

Correct answer: A — Conservative force

Conservative forces (like gravity) are those for which potential energy can be defined, meaning the force is associated with potential energy changes.

Correct answer: B — Conservative forces

Mechanical energy is conserved if only conservative forces are doing work, as conservative forces do not change the total mechanical energy of the system.

Correct answer: A — Conservative forces

Conservative forces (like gravity or spring force) are path-independent; the work done by them depends only on the initial and final positions, not the path taken. Non-conservative forces (like friction) are path-dependent.

Correct answer: C — Independent of the path

For a conservative force, the work done is independent of the path taken between the starting and ending points. This is the defining characteristic of conservative forces.

Correct answer: C — Potential Energy

For a conservative force, the work done is related to the change in potential energy (W = -ΔU).

Correct answer: A — It decreases

When non-conservative forces (like friction) are present, they dissipate energy, meaning the total mechanical energy of the system is not conserved; it decreases.

Correct answer: D — Mechanical Energy

The work done by non-conservative forces (like friction) is responsible for the change in the total mechanical energy of the system (Work-Energy Theorem applied to non-conservative forces).

Correct answer: D — Conservative forces

Mechanical energy is conserved only when the net work done by the forces acting on the system is zero, which occurs when the forces are conservative (e.g., gravity). Non-conservative forces (like friction) always result in a change in mechanical energy.

Correct answer: D — Gravitational force

Gravitational force is a conservative force because the work done by it depends only on the initial and final positions, not the path taken. Friction and air resistance are non-conservative forces, and applied forces are general terms.

Correct answer: A — Mechanical Energy

Non-conservative forces dissipate mechanical energy into other forms, usually thermal energy (heat), meaning mechanical energy is not conserved in the presence of these forces.

Correct answer: C — Mechanical energy is conserved

When only conservative forces are doing work, the net work done on the system is equal to the change in potential energy, ensuring that the total mechanical energy remains constant (is conserved).

Correct answer: A — Kinetic friction

Kinetic friction is a non-conservative force because the work done by friction depends on the path over which the object moves. Tension, normal force, and electrostatic forces are generally conservative (or derivable from a potential).