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A wave in a rope travels at 12 m/s and has a wavelength of 2 m. What is the frequency?
- A. 38.4 Hz
- B. 6 Hz
- C. 4.6 Hz
- D. 3.75 Hz
Correct Answer: B
Rationale: The frequency of a wave is calculated using the formula: frequency = speed / wavelength. In this case, the speed of the wave is 12 m/s and the wavelength is 2 m. Therefore, the frequency is calculated as 12 m/s / 2 m = 6 Hz. Choice A (38.4 Hz), Choice C (4.6 Hz), and Choice D (3.75 Hz) are incorrect as they do not result from the correct calculation using the given values.
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Four 5 V batteries are connected in series. What is the total voltage of the circuit?
- A. 5.0 V
- B. 10.0 V
- C. 15.0 V
- D. 20.0 V
Correct Answer: D
Rationale: When batteries are connected in series, their voltages add up. Therefore, the total voltage of the circuit with four 5 V batteries connected in series will be 5 V + 5 V + 5 V + 5 V = 20 V. Choices A, B, and C are incorrect because the voltages of the batteries add up in series, resulting in a total of 20 V.
A bicycle and a car are both traveling at a rate of 5 m/s. Which statement is true?
- A. The bicycle has more kinetic energy than the car.
- B. The bicycle has less kinetic energy than the car.
- C. Both vehicles have the same amount of kinetic energy.
- D. Only the car has kinetic energy.
Correct Answer: B
Rationale: Kinetic energy is determined by both the mass and the velocity of an object. While both the bicycle and the car are moving at the same velocity (5 m/s), the car has significantly more mass than the bicycle. As a result, the car has more kinetic energy than the bicycle, even though their speeds are identical. Therefore, choice B is correct. Choices A, C, and D are incorrect because they do not consider the influence of mass on kinetic energy. Choice A is incorrect as the car has more kinetic energy due to its greater mass. Choice C is incorrect because the vehicles have different masses. Choice D is incorrect as both the bicycle and the car possess kinetic energy.
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.
A 110-volt hair dryer delivers 1,525 watts of power. How many amperes does it draw?
- A. 167.75 amperes
- B. 1.635 amperes
- C. 1.415 amperes
- D. 13.9 amperes
Correct Answer: D
Rationale: To determine the amperes drawn by the hair dryer, we use the formula: Amperes = Watts / Volts. The hair dryer operates at 1,525 watts with 110 volts. Dividing 1,525 watts by 110 volts yields 13.9 amperes. Therefore, the correct answer is 13.9 amperes. Choices A, B, and C are incorrect because they do not result from the correct calculation using the formula.
A 5-cm candle is placed 20 cm away from a concave mirror with a focal length of 10 cm. What is the image distance of the candle?
- A. 20 cm
- B. 40 cm
- C. 60 cm
- D. 75 cm
Correct Answer: C
Rationale: To find the image distance of the candle, we use the mirror formula: 1/f = 1/do + 1/di, where f is the focal length, do is the object distance, and di is the image distance. In this case, the focal length f = 10 cm and the object distance do = 20 cm. Substituting these values into the formula gives us 1/10 = 1/20 + 1/di. Solving for di, we get di = 60 cm. Therefore, the image distance of the candle is 60 cm. Choice A (20 cm) is incorrect because it represents the object distance, not the image distance. Choice B (40 cm) is incorrect as it does not consider the mirror formula calculation. Choice D (75 cm) is incorrect as it does not match the correct calculation based on the mirror formula.