HESI A2
HESI A2 Physics Practice Test
1. If the force acting on an object is doubled, how does its acceleration change?
- A. It remains the same.
- B. It is halved.
- C. It is doubled.
- D. It is eliminated.
Correct answer: C
Rationale: According to Newton's second law of motion, the acceleration of an object is directly proportional to the force acting on it. Therefore, if the force acting on an object is doubled, its acceleration will also double. This relationship is expressed by the equation F = ma, where F is the force, m is the mass of the object, and a is the acceleration. When the force (F) is doubled, the acceleration (a) will also double, assuming the mass remains constant. Choice A is incorrect because acceleration changes with a change in force. Choice B is incorrect because acceleration and force are directly proportional. Choice D is incorrect because increasing the force acting on an object does not eliminate its acceleration; instead, it results in an increase in acceleration, as per Newton's second law.
2. The amount of energy lost in a circuit due to electrical resistance is dissipated in the form of:
- A. Light
- B. Sound
- C. Heat
- D. Mechanical work
Correct answer: C
Rationale: When electrical current flows through a circuit with resistance, energy is lost in the form of heat due to the resistance encountered by the electrons. This dissipation of energy as heat is a common phenomenon in electrical circuits and is known as Joule heating. Therefore, the correct answer is 'Heat.' Light, sound, and mechanical work are not typical forms in which energy is lost due to electrical resistance. Light is not a direct result of energy dissipation in electrical circuits, sound is not a form of energy dissipation in this context, and mechanical work pertains to the application of physical force and not the dissipation of energy due to resistance.
3. 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.
4. 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 (Ï) only
- B. Viscosity (μ) only
- C. Density (Ï) and Bulk modulus
- D. Density (Ï) and Surface tension (γ)
Correct answer: C
Rationale: In a compressible fluid, the speed of sound (c) depends on both the fluid's density (Ï) 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.
5. A 3-volt flashlight uses a bulb with 60-ohm resistance. What current flows through the flashlight?
- A. o.05 amp
- B. o.5 amp
- C. 1.8 amp
- D. 18 amp
Correct answer: A
Rationale: : Using Ohm's Law, I = V / R: I = 3 / 60 = 0.05 amp. So, the correct current is 0.05 amp.
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