Nokea
Which of these objects has the greatest momentum?
- A. A 1,250-kg car moving at 5 m/s
- B. An 80-kg person running at 4 m/s
- C. A 10-kg piece of meteorite moving at 600 m/s
- D. A o.5-kg rock moving at 40 m/s
Correct Answer: A
Rationale: Momentum is the product of mass and velocity. The car has the highest momentum because it has the largest mass and a significant velocity.
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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 system undergoes an isobaric process (constant pressure). In this process, the work done (W) by the system is:
- A. Zero, if the volume change (ΔV) is zero.
- B. Positive and equal to the pressure multiplied by the volume change (W = PΔV).
- C. Negative and equal to the pressure multiplied by the volume change.
- D. Independent of the pressure or volume change.
Correct Answer: B
Rationale: In an isobaric process (constant pressure), the work done is given by the formula W = PΔV, where P is the pressure and ΔV is the change in volume. If the volume does not change, the work done is zero, not negative. Choice A is incorrect as it states the work done is zero when the volume change is zero, which is the correct condition for zero work. Choice C is incorrect as it incorrectly suggests that the work done is negative in an isobaric process. Choice D is incorrect as the work done in an isobaric process is indeed dependent on the volume change and pressure.
Sublimation is the change in matter from solid to gas or gas to solid without passing through a liquid phase. Outside of the laboratory, which solid provides the best example of this?
- A. Iron
- B. Silver
- C. Salt crystal
- D. Dry ice
Correct Answer: D
Rationale: Dry ice (solid carbon dioxide) provides the best example of sublimation outside of the laboratory. When dry ice is exposed to normal atmospheric conditions, it changes directly from a solid to a gas without passing through a liquid phase. This process is commonly observed in everyday situations such as creating 'smoke' or 'fog' effects. Choices A, B, and C (Iron, Silver, and Salt crystal) do not undergo sublimation. Iron and Silver melt and then vaporize, while Salt crystal dissolves in water, and the resulting solution evaporates, which involves a liquid phase.
When a charged particle moves through a vacuum at a constant speed, it generates:
- A. An electric field only
- B. A magnetic field only
- C. Both an electric and magnetic field
- D. Neither an electric nor magnetic field
Correct Answer: C
Rationale: A moving charged particle generates both an electric field and a magnetic field. The electric field is due to the charge itself, and the magnetic field is produced by the motion of the charge. Choice A is incorrect because a moving charged particle also generates a magnetic field. Choice B is incorrect because a moving charged particle generates both electric and magnetic fields. Choice D is incorrect as a moving charged particle generates fields due to its charge and motion.
Archimedes' principle explains the ability to control buoyancy, allowing:
- A. Objects to sink regardless of density differences.
- B. Airplanes to generate lift for flight.
- C. Submarines to adjust their buoyancy for submergence and resurfacing.
- D. Helium balloons to overcome gravity and float.
Correct Answer: C
Rationale: Archimedes' principle states that the upward buoyant force acting on an object submerged in a fluid is equal to the weight of the fluid displaced by the object. Submarines control their buoyancy by adjusting the volume of water they displace, which allows them to submerge and resurface. Choice C is correct because it directly relates to the principle of buoyancy and how submarines utilize it. Choices A, B, and D are incorrect because they do not accurately reflect the application of Archimedes' principle in controlling buoyancy for submergence and resurfacing.