HESI A2
HESI A2 Physics
1. Longitudinal waves have vibrations that move ___________.
- A. at right angles to the direction of the vibrations
- B. in the direction opposite to that of the wave
- C. in the same direction as the wave
- D. in waves and troughs
Correct answer: C
Rationale: In longitudinal waves, the vibrations of particles occur in the same direction as the wave propagates. This means the particles move back and forth in the direction of the wave, creating compressions and rarefactions along the wave. Therefore, the correct choice is C, in the same direction as the wave. Choice A is incorrect because transverse waves, not longitudinal waves, have vibrations at right angles to the direction of wave propagation. Choice B is incorrect as it describes the motion in transverse waves. Choice D is incorrect as it is an inaccurate representation of how longitudinal waves propagate.
2. As a vehicle positioned at the peak of a hill rolls downhill, its potential energy transforms into:
- A. Thermal energy
- B. Neither thermal nor kinetic energy
- C. A combination of thermal and kinetic energy
- D. Kinetic energy
Correct answer: D
Rationale: The correct answer is D: Kinetic energy. Potential energy is converted into kinetic energy as the vehicle moves downhill. Kinetic energy is the energy possessed by a moving object. Thermal energy is not produced in this scenario because the energy transformation is mainly from potential to kinetic energy, not involving heat generation. Choices A, B, and C are incorrect because the primary energy transformation in this scenario is from potential to kinetic energy, not involving thermal energy.
3. 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.
4. A 780-watt refrigerator is powered by a 120-volt power source. What is the current being drawn?
- A. 660 amperes
- B. 150 amperes
- C. 6.5 amperes
- D. 0.15 amperes
Correct answer: C
Rationale: To calculate the current being drawn by the refrigerator, you can use the formula: Current (I) = Power (P) / Voltage (V). Given that the power of the refrigerator is 780 watts and the voltage is 120 volts, you can plug these values into the formula to find the current: I = 780 watts / 120 volts = 6.5 amperes. Therefore, the current being drawn by the 780-watt refrigerator is 6.5 amperes. Choice A, 660 amperes, is incorrect as it is significantly higher than the correct answer. Choice B, 150 amperes, is also incorrect and too high. Choice D, 0.15 amperes, is incorrect as it is too low. The correct answer is 6.5 amperes.
5. Ocean waves build during a storm until there is a vertical distance from the high point to the low point of 6 meters and a horizontal distance of 9 meters between adjacent crests. The waves hit the shore every 5 seconds. What is the speed of the waves?
- A. 1.2 m/s
- B. 1.8 m/s
- C. 2.0 m/s
- D. 2.4 m/s
Correct answer: B
Rationale: To find the speed of the waves, we use the formula: speed = wavelength / period. The wavelength is the horizontal distance between adjacent crests, which is 9 meters in this case. The period is the time it takes for one wave to pass a fixed point, given as 5 seconds. Therefore, speed = 9 meters / 5 seconds = 1.8 m/s. Choice A (1.2 m/s) is incorrect because it miscalculates the speed. Choice C (2.0 m/s) and Choice D (2.4 m/s) are incorrect as they do not correctly calculate the speed using the provided data.
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