Nokea
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.
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A wave moves through its medium at 20 m/s with a wavelength of 4 m. What is the frequency of the wave?
- A. 5 s−1
- B. 16 s−1
- C. 24 s−1
- D. 80 s−1
Correct Answer: C
Rationale: The formula to calculate the frequency of a wave is given by:
An incandescent lamp consumes 60 Joules of energy per second. What is the power rating of this lamp?
- A. 1 Watt (W)
- B. 60 Watts (W)
- C. 1/60 Joules
- D. Impossible to determine without knowing the voltage
Correct Answer: B
Rationale: Power is defined as energy consumed per unit time. If the lamp consumes 60 Joules of energy per second, the power rating is 60 Watts. Therefore, choice B is correct. Choice A ('1 Watt') is incorrect because the lamp consumes 60 Joules per second, not 1 Joule per second. Choice C ('1/60 Joules') is incorrect as it does not represent the power rating. Choice D ('Impossible to determine without knowing the voltage') is incorrect because power can be calculated using energy consumption per unit time without needing to know the voltage.
In hydraulic systems, Pascal's principle states that a pressure change applied to a confined incompressible fluid is:
- A. Amplified but loses energy
- B. Transmitted undiminished throughout the fluid
- C. Limited by the container size
- D. Dependent on the fluid type
Correct Answer: B
Rationale: Pascal's principle states that when a pressure change is applied to a confined incompressible fluid, the resulting pressure change is transmitted undiminished throughout the fluid. This means that the pressure change will be the same at every point in the fluid, regardless of the container size or the type of fluid used. Therefore, choice B is the correct answer. Choices A, C, and D are incorrect because Pascal's principle specifically emphasizes the transmission of pressure without amplification, limitation by container size, or dependence on the fluid type.
What is the primary factor responsible for generating lift on an airplane wing?
- A. Propulsion force generated by the engines
- B. Buoyant forces acting on the entire aircraft
- C. Drag reduction achieved through streamlining
- D. Application of Bernoulli's principle to the airfoil's shape
Correct Answer: D
Rationale: The primary factor responsible for generating lift on an airplane wing is the application of Bernoulli's principle. This principle states that the air moving over the curved top surface of the wing has to travel faster, leading to reduced pressure above the wing and creating lift. Engines provide thrust for propulsion, not lift. Buoyant forces are more relevant to lighter-than-air aircraft like balloons or airships, not airplanes. While drag reduction through streamlining is important for efficiency, it is not the primary factor in lift generation. Therefore, the correct answer is D.
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.