Mechanical energy of a body includes __________.

Question

Examoogle · Accepted Answer

The correct answer is Option C: both potential energy and kinetic energy. Mechanical energy is defined as the sum of the potential energy and kinetic energy possessed by an object. It represents the total energy associated with the motion and position of an object in a mechanical system.

Step-by-Step Solution & Concepts:
Mechanical energy is defined as the sum of the potential energy and kinetic energy possessed by an object. It represents the total energy associated with the motion and position of an object in a mechanical system.

Working Principle: According to the principle of conservation of mechanical energy, for a system under conservative forces (like gravity or spring forces), the total mechanical energy remains constant. Kinetic energy is associated with the motion of the body ($E_k = \frac{1}{2}mv^2$), while potential energy is associated with the body's configuration or position within a force field ($U = mgh$ or $U = \frac{1}{2}kx^2$).

Key Formulas: $E_{mechanical} = E_k + U$ — Total mechanical energy is the sum of kinetic ($E_k$) and potential ($U$) energy.; $E_k = \frac{1}{2}mv^2$ — Kinetic energy of a body with mass $m$ and velocity $v$.; $U_g = mgh$ — Gravitational potential energy at height $h$.

Key Points: Mechanical energy is a scalar quantity measured in Joules (J).; It only accounts for energy related to position and motion, excluding internal energies like thermal or chemical energy.; The law of conservation of energy applies to mechanical energy in the absence of non-conservative forces like friction or air resistance.

Advantages: Useful for calculating the trajectory and velocity of objects in simplified physical systems.

Disadvantages: Does not account for energy loss due to friction, air resistance, or sound, which are non-conservative forces.

Applications: Analyzing roller coaster tracks.; Predicting the behavior of simple pendulums and oscillating springs.

Additional Info: If non-conservative forces like friction are present, mechanical energy is converted into other forms, most commonly heat energy.. Wrong options explanation: Kinetic energy and potential energy are individual components; 'heat energy' is not a component of mechanical energy.

Answer: C is correct — Mechanical energy is the sum of both the kinetic and potential energy of a body.

Exam Tip: Always remember that in competitive physics, 'mechanical energy' is synonymous with 'total energy' only in systems where no dissipative forces like friction are explicitly mentioned.

Examoogle · Answer

Option A: kinetic energy only

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Option B: heat energy only

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Option D: potential energy only

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