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How do a scalar quantity and a vector quantity differ?
- A. A scalar quantity has both magnitude and direction, and a vector does not.
- B. A scalar quantity has direction only, and a vector has only magnitude.
- C. A vector has both magnitude and direction, and a scalar quantity has only magnitude.
- D. A vector has only direction, and a scalar quantity has only magnitude.
Correct Answer: C
Rationale: The correct answer is C. The main difference between a scalar quantity and a vector quantity lies in the presence of direction. A vector quantity has both magnitude and direction, while a scalar quantity has magnitude only, without any specified direction. Examples of scalar quantities include distance, speed, temperature, and energy, whereas examples of vector quantities include displacement, velocity, force, and acceleration. Choices A, B, and D are incorrect because they incorrectly describe the characteristics of scalar and vector quantities.
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Two objects attract each other with a gravitational force of 12 units. If you double the distance between the objects, what is the new force of attraction between the two?
- A. 3 units
- B. 6 units
- C. 24 units
- D. 48 units
Correct Answer: A
Rationale: The gravitational force between two objects is inversely proportional to the square of the distance between them. If the distance is doubled, the force will be reduced to 1/4 of the original force. Therefore, the new force of attraction between the two objects will be 12 units / 4 = 3 units. Choice A is correct because doubling the distance reduces the force to 1/4 of the original value. Choices B, C, and D are incorrect as they do not consider the inverse square relationship between distance and gravitational force.
A 0-kg block on a table is given a push so that it slides along the table. If the block is accelerated at 6 m/s2, what was the force applied to the block?
- A. 0 N
- B. 3 N
- C. 6 N
- D. The answer cannot be determined from the information given.
Correct Answer: A
Rationale: According to Newton's second law of motion,
F=ma. Since the block has a mass of 0 kg, the force applied must be 0 N, as no force is needed to move an object with zero mass.
A 2,000-kg car travels at 15 m/s. For a 1,500-kg car traveling at 15 m/s to generate the same momentum, what would need to happen?
- A. It would need to accelerate to 20 m/s.
- B. It would need to add 500 kg in mass.
- C. Both A and B
- D. Either A or B
Correct Answer: A
Rationale: Momentum is calculated as the product of mass and velocity. Since momentum is conserved in the absence of external forces, for the 1,500-kg car to generate the same momentum as the 2,000-kg car at 15 m/s, it would need to increase its velocity to compensate for the difference in mass. Accelerating to 20 m/s would achieve this without needing to change the mass of the car. Choice B is incorrect because adding mass is not necessary to match momentum in this scenario.
Diamagnetism refers to a material's weak:
- A. Attraction to magnetic fields
- B. Repulsion to magnetic fields
- C. Amplification of magnetic fields
- D. Indifference to magnetic fields
Correct Answer: B
Rationale: Diamagnetism refers to a material's weak repulsion to magnetic fields. When diamagnetic materials are placed in an external magnetic field, they create an opposing magnetic field, leading to repulsion. This is why choice B, 'Repulsion to magnetic fields,' is the correct answer. Choices A, C, and D are incorrect because diamagnetic materials do not exhibit attraction, amplification, or indifference to magnetic fields.
A 60-watt lightbulb is powered by a 110-volt power source. What is the current being drawn?
- A. 0.55 amperes
- B. 1.83 amperes
- C. 50 amperes
- D. 6,600 amperes
Correct Answer: A
Rationale: To calculate the current being drawn, use the formula I = P / V, where I is the current, P is the power in watts, and V is the voltage. Substituting the given values, I = 60 / 110 ≈ 0.55 amperes. Therefore, the current being drawn by the 60-watt lightbulb is approximately 0.55 amperes. Choice B, 1.83 amperes, is incorrect as it does not match the calculated value. Choices C and D, 50 amperes and 6,600 amperes, are significantly higher values and do not align with the expected current draw of a 60-watt lightbulb powered by a 110-volt source.