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Jack stands in front of a plane mirror. If he is 5 feet away from the mirror, how far away from Jack is his image?
- A. 2.5 feet
- B. 3 feet
- C. 4.5 feet
- D. 5 feet
Correct Answer: D
Rationale: When Jack stands in front of a plane mirror, his image appears the same distance behind the mirror as Jack is in front of it. Therefore, if Jack is 5 feet away from the mirror, his image will also appear 5 feet behind the mirror. The total distance from Jack to his image is the sum of these distances, which equals 10 feet. Choices A, B, and C are incorrect because the image distance is not half of the total distance but the same as the object's distance from the mirror.
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What is the kinetic energy of a 500-kg wagon moving at 10 m/s?
- A. 50 J
- B. 250 J
- C. 2.5 10^4 J
- D. 5.0 10^5 J
Correct Answer: C
Rationale: The formula for calculating kinetic energy is KE = 0.5 mass velocity². Given the mass of the wagon is 500 kg and the velocity is 10 m/s, we can substitute these values into the formula: KE = 0.5 500 kg (10 m/s)² = 0.5 500 kg 100 m²/s² = 25,000 J or 2.5 10â´ J. Therefore, the kinetic energy of the 500-kg wagon moving at 10 m/s is 2.5 10â´ J. Choice A (50 J) is incorrect because it is too low; Choice B (250 J) is incorrect as it does not match the correct calculation; Choice D (5.0 10^5 J) is incorrect as it is too high. The correct answer is C (2.5 10^4 J).
In a scenario where a transverse wave transports energy from north to south, in what direction do the particles in the medium move?
- A. Only north to south
- B. Both northward and southward
- C. Only east to west
- D. Both eastward and westward
Correct Answer: B
Rationale: In a transverse wave, particles of the medium move perpendicular to the direction of energy transport. When the wave transports energy from north to south, the particles in the medium oscillate up and down, causing them to move both northward and southward. Choice A is incorrect because the particles move in both directions, not only from north to south. Choices C and D are incorrect as they mention directions that are not relevant to the scenario described in the question.
Certain non-Newtonian fluids exhibit shear thickening behavior. In this case, the fluid's viscosity:
- A. Remains constant with increasing shear rate
- B. Decreases with increasing shear rate (shear thinning)
- C. Increases with increasing shear rate
- D. Depends solely on the applied pressure
Correct Answer: C
Rationale: When a non-Newtonian fluid exhibits shear thickening behavior, its viscosity increases with increasing shear rate. This means that as more force is applied to the fluid, its resistance to flow also increases, resulting in a higher viscosity. This phenomenon is opposite to shear thinning, where viscosity decreases with increasing shear rate. Therefore, in the case of shear thickening behavior, the correct answer is that the fluid's viscosity increases with increasing shear rate. Choices A, B, and D are incorrect because shear thickening behavior specifically involves an increase in viscosity with increasing shear rate, not remaining constant, decreasing, or depending on applied pressure.
An object has a constant velocity of 50 m/s and travels for 10 s. What is the acceleration of the object?
- A. 0 m/s²
- B. 5 m/s²
- C. 60 m/s²
- D. 500 m/s²
Correct Answer: A
Rationale: The acceleration of an object is defined as the rate of change of its velocity. When an object has a constant velocity, it means there is no change in its speed or direction. In this case, the object maintains a constant velocity of 50 m/s for 10 seconds, which implies that there is no change in velocity. Therefore, the acceleration of the object is 0 m/s² as there is no acceleration or deceleration happening. Choices B, C, and D are incorrect because acceleration is the change in velocity over time, and in this scenario of constant velocity, the acceleration is 0 m/s².
Household alternating current typically has a frequency of 60 Hz. Which statement is true?
- A. The circuit is suitable for lighting 60-watt bulbs.
- B. Circuits in the home may carry a current of 60 amperes.
- C. The expected voltage drop is 60 volts per meter.
- D. Electrons complete a cycle 60 times per second.
Correct Answer: D
Rationale: The correct answer is D. Electrons complete a cycle 60 times per second when the frequency of the current is 60 Hz. This frequency indicates that the current changes direction 60 times per second, causing the electrons to complete a full cycle back and forth through the circuit at the same rate. Choice A is incorrect because the power rating of a bulb (in watts) is not directly related to the frequency of the current. Choice B is incorrect as typical household circuits do not carry currents as high as 60 amperes. Choice C is incorrect as the expected voltage drop is not measured in volts per meter for household alternating current circuits.