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Which of the following forces does NOT conserve mechanical energy?
Gravitational force
Frictional force
Spring force
Electrostatic force
Frictional force
Frictional force is a non-conservative force because the work done by it depends on the path taken and results in the dissipation of mechanical energy into non-recoverable forms like heat. In contrast, conservative forces like gravitational, spring, and electrostatic forces allow for the total mechanical energy of a system to remain constant.
Frictional force is a non-conservative force because the work done by it depends on the path taken and results in the dissipation of mechanical energy into non-recoverable forms like heat. In contrast, conservative forces like gravitational, spring, and electrostatic forces allow for the total mechanical energy of a system to remain constant.
Pushing a box across a rough floor is like spending money at a store; the heat generated by friction is like a 'service fee' that disappears, whereas conservative forces are like moving money between two savings accounts where no value is lost.
NC-F (Non-Conservative = Friction)
W=тИлFтЛЕdr тАФ Work done by a force
EmechanicalтАЛ=K+U тАФ Total mechanical energy
WncтАЛ=╬ФE тАФ Work-energy theorem for non-conservative forces
In a conservative force field, the work done in a closed loop is zero, and the force is derivable from a potential energy function. Frictional force acts opposite to the direction of motion, converting kinetic energy into thermal energy (Q=тИлfkтАЛdx), which cannot be fully transformed back into mechanical energy.
Conservative forces: Gravitational, Electrostatic, Magnetic (on charges), and Spring forces.
Non-conservative forces: Friction, Viscosity, and Air resistance.
Energy dissipated by friction is typically released as thermal energy (heat).
Mechanical energy is conserved only when the work done by non-conservative forces is zero.
Friction allows for traction and grip, essential for walking and vehicle braking.
Friction causes wear and tear in machinery.
Friction leads to energy loss as waste heat.
Braking systems in automobiles
Designing aerodynamic profiles to minimize drag
| Feature | Conservative Force | Non-conservative Force |
|---|---|---|
Work along closed path | Zero | Non-zero |
The work done by a conservative force depends only on the initial and final positions.
Option A, C, and D are conservative because they are associated with potential energy fields.
B is correct тАФ Frictional force is a non-conservative force that dissipates mechanical energy into heat.
Always remember that if a force is path-dependent, it is almost certainly non-conservative, and mechanical energy will not be conserved in its presence.
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