HESI A2
HESI A2 Physics
1. For a compressible fluid subjected to rapid pressure changes, sound wave propagation becomes important. The speed of sound (c) depends on the fluid's:
- A. Density (ρ) only
- B. Viscosity (μ) only
- C. Density (ρ) and Bulk modulus
- D. Density (ρ) and Surface tension (γ)
Correct answer: C
Rationale: In a compressible fluid, the speed of sound (c) depends on both the fluid's density (ρ) and Bulk modulus. Density affects the compressibility of the fluid, while Bulk modulus represents the fluid's resistance to compression and plays a crucial role in determining the speed of sound in a compressible medium. Viscosity and surface tension do not directly impact the speed of sound in a compressible fluid subjected to rapid pressure changes. Therefore, the correct answer is C.
2. In physics, the relationship between acceleration and force is expressed in ___________.
- A. Newton’s first law of motion
- B. Newton’s second law of motion
- C. Newton’s third law of motion
- D. none of Newton’s laws of motion
Correct answer: B
Rationale: The relationship between acceleration and force is expressed in Newton’s second law of motion. This law states that the acceleration of an object is directly proportional to the net force acting on the object and inversely proportional to the object's mass. Mathematically, this relationship is represented as F = ma, where F is the force, m is the mass of the object, and a is the acceleration. Choice A, Newton’s first law of motion, also known as the law of inertia, states that an object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an external force. Choice C, Newton’s third law of motion, states that for every action, there is an equal and opposite reaction, focusing on the interaction between two objects. Choice D is incorrect because the relationship between acceleration and force is indeed described by one of Newton’s laws of motion, specifically the second law.
3. What is the phenomenon by which light bends as it passes through a prism known as?
- A. Reflection
- B. Electrical conduction
- C. Diffraction
- D. Refraction
Correct answer: D
Rationale: Refraction is the phenomenon by which light bends as it passes through a prism or any other medium boundary. When light transitions from one medium to another, such as air to glass in the case of a prism, it changes speed and direction due to the change in the medium's refractive index. This change in speed causes the light to bend. Reflection, on the other hand, is the bouncing back of light when it hits a surface. Diffraction refers to the bending of light around obstacles or through narrow openings. Electrical conduction involves the movement of electrically charged particles through a conductor, which is unrelated to the bending of light.
4. In the mechanical power equation P = E / t, power is measured in ___________.
- A. ohms
- B. Joules
- C. volts
- D. watts
Correct answer: D
Rationale: In the mechanical power equation P = E / t, power is measured in watts. Watts are the standard unit of power in the International System of Units (SI), named after the Scottish engineer James Watt. Watts are defined as joules per second, reflecting the rate at which energy is transferred or converted. Ohms (choice A) are the unit of electrical resistance, Joules (choice B) are the unit of energy, and volts (choice C) are the unit of electric potential difference. Therefore, the correct answer is watts as it directly relates to power in the given equation.
5. Energy manifests in various forms. Which of the following is NOT considered a fundamental energy type?
- A. Thermal energy
- B. Momentum
- C. Sound energy
- D. Chemical energy
Correct answer: B
Rationale: The correct answer is B. Momentum is not considered a form of energy; it is a property of moving objects. Thermal, sound, and chemical energy are all forms of energy. Thermal energy is the energy associated with the movement of particles within an object. Sound energy is produced by vibrations and travels through materials as waves. Chemical energy is stored within the bonds of chemical compounds. While momentum is a crucial concept in physics, it is not a fundamental form of energy.
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