HESI A2
HESI A2 Physics Quizlet
1. A caterpillar starts moving at a rate of 14 in/hr. After 15 minutes, it is moving at a rate of 20 in/hr. What is the caterpillar’s rate of acceleration?
- A. 6 in/hr²
- B. 12 in/hr²
- C. 24 in/hr²
- D. 280 in/hr²
Correct answer: C
Rationale: Acceleration is the change in velocity over time. The change in velocity for the caterpillar is 20 in/hr - 14 in/hr = 6 in/hr. Since this change occurred over 15 minutes (or 0.25 hours), the acceleration can be calculated as (6 in/hr) / (0.25 hr) = 24 in/hr². Therefore, the caterpillar's rate of acceleration is 24 in/hr², which corresponds to choice C. Choice A, 6 in/hr², is incorrect as it does not account for the time factor and the correct calculation. Choice B, 12 in/hr², is incorrect as it doubles the correct acceleration value. Choice D, 280 in/hr², is significantly higher than the correct value, indicating a calculation error.
2. Enthalpy (H) is a thermodynamic property defined as the sum of a system's internal energy (U) and the product of its pressure (P) and volume (V). The relationship between these is:
- A. H = U + PV
- B. H = U - PV
- C. H = U / PV
- D. H = PV / U
Correct answer: A
Rationale: Enthalpy (H) is defined as H = U + PV, where U represents internal energy, P is pressure, and V is volume. Enthalpy includes both the internal energy of a system and the energy required to create space for the system against an external pressure. Therefore, the correct relationship between enthalpy, internal energy, pressure, and volume is H = U + PV. Choice B is incorrect as subtracting PV would not account for the work done against pressure. Choice C is incorrect as dividing U by PV doesn't represent the definition of enthalpy. Choice D is incorrect as dividing PV by U is not the correct relationship based on the definition of enthalpy.
3. According to the Law of Universal Gravitation, the gravitational force between two objects is directly proportional to what factor?
- A. the gravitational constant
- B. the distance between them
- C. the product of their masses
- D. the square of the distance between them
Correct answer: C
Rationale: According to the Law of Universal Gravitation, the gravitational force between two objects is directly proportional to the product of their masses. The equation is: F = G × (m₠× m₂) / r², where F is the gravitational force, G is the gravitational constant, m₠and m₂ are the masses of the two objects, and r is the distance between them. Choice A is incorrect because the gravitational constant is a constant value. Choice B is incorrect because the distance between the objects affects the strength of the gravitational force inversely proportional to the square of the distance, not directly proportional. Choice D is incorrect as it represents the inverse square law, where the gravitational force decreases with the square of the distance between the objects.
4. How do you determine the velocity of a wave?
- A. Multiply the frequency by the wavelength.
- B. Add the frequency and the wavelength.
- C. Subtract the wavelength from the frequency.
- D. Divide the wavelength by the frequency.
Correct answer: A
Rationale: The velocity of a wave can be determined by multiplying the frequency of the wave by the wavelength. This relationship is given by the formula: velocity = frequency × wavelength. By multiplying the frequency by the wavelength, you can calculate the speed at which the wave is traveling. This formula is derived from the basic wave equation v = f × λ, where v represents velocity, f is frequency, and λ is wavelength. Therefore, to find the velocity of a wave, one must multiply its frequency by its wavelength. Choices B, C, and D are incorrect. Adding, subtracting, or dividing the frequency and wavelength does not yield the correct calculation for wave velocity. The correct formula for determining wave velocity is to multiply the frequency by the wavelength.
5. A rock has a volume of 6 cm3 and a mass of 24 g. What is its density?
- A. 4 g/cm3
- B. 4 cm3/g
- C. 144 g/cm3
- D. 144 cm3/g
Correct answer: A
Rationale: Density is calculated by dividing the mass of an object by its volume. In this case, the mass of the rock is 24 g and its volume is 6 cm3. By dividing 24 g by 6 cm3, we find that the density of the rock is 4 g/cm3. Choice A is the correct answer because density is expressed in units of mass per unit volume (g/cm3). Choice B is incorrect as it represents the reciprocal of density. Choices C and D are significantly higher values and do not match the calculated density of the rock.
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