Nokea
In fluid machinery, pumps are designed to primarily increase the fluid's:
- A. Pressure
- B. Velocity only
- C. Both pressure and velocity
- D. Neither pressure nor velocity
Correct Answer: A
Rationale: Pumps in fluid machinery are designed to primarily increase the fluid's pressure. This increase in pressure allows the fluid to flow through the system efficiently and overcome resistance. While pumps can also impact the velocity of the fluid to some extent, their main function is to elevate the pressure to facilitate the movement of the fluid within the system. Choice B is incorrect because pumps do not focus solely on increasing velocity. Choice C is incorrect as while pumps can affect velocity, their primary purpose is to boost pressure. Choice D is incorrect as pumps aim to increase either the pressure, velocity, or both.
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In physics, the relationship between acceleration and force is expressed in ___________.
- A. Newton's first law of motion
- B. Newton's second law of motion
- C. Newton's third law of motion
- D. none of Newton's laws of motion
Correct Answer: B
Rationale: The relationship between acceleration and force is expressed in Newton's second law of motion. This law states that the acceleration of an object is directly proportional to the net force acting on the object and inversely proportional to the object's mass. Mathematically, this relationship is represented as F = ma, where F is the force, m is the mass of the object, and a is the acceleration. Choice A, Newton's first law of motion, also known as the law of inertia, states that an object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an external force. Choice C, Newton's third law of motion, states that for every action, there is an equal and opposite reaction, focusing on the interaction between two objects. Choice D is incorrect because the relationship between acceleration and force is indeed described by one of Newton's laws of motion, specifically the second law.
For a compressible fluid subjected to rapid pressure changes, sound wave propagation becomes important. The speed of sound (c) depends on the fluid's:
- A. Density (Ï) only
- B. Viscosity (μ) only
- C. Density (Ï) and Bulk modulus
- D. Density (Ï) and Surface tension (γ)
Correct Answer: C
Rationale: In a compressible fluid, the speed of sound (c) depends on both the fluid's density (Ï) and Bulk modulus. Density affects the compressibility of the fluid, while Bulk modulus represents the fluid's resistance to compression and plays a crucial role in determining the speed of sound in a compressible medium. Viscosity and surface tension do not directly impact the speed of sound in a compressible fluid subjected to rapid pressure changes. Therefore, the correct answer is C.
How do you determine the velocity of a wave?
- A. Multiply the frequency by the wavelength.
- B. Add the frequency and the wavelength.
- C. Subtract the wavelength from the frequency.
- D. Divide the wavelength by the frequency.
Correct Answer: A
Rationale: The velocity of a wave can be determined by multiplying the frequency of the wave by the wavelength. This relationship is given by the formula: velocity = frequency wavelength. By multiplying the frequency by the wavelength, you can calculate the speed at which the wave is traveling. This formula is derived from the basic wave equation v = f λ, where v represents velocity, f is frequency, and λ is wavelength. Therefore, to find the velocity of a wave, one must multiply its frequency by its wavelength. Choices B, C, and D are incorrect. Adding, subtracting, or dividing the frequency and wavelength does not yield the correct calculation for wave velocity. The correct formula for determining wave velocity is to multiply the frequency by the wavelength.
A solenoid is a long, tightly wound coil of wire that acts like a bar magnet when current flows through it. The magnetic field lines inside a solenoid are most similar to the field lines around:
- A. A single straight current-carrying wire
- B. A horseshoe magnet
- C. A permanent bar magnet
- D. A flat sheet conductor
Correct Answer: C
Rationale: The magnetic field lines inside a solenoid resemble the field lines around a permanent bar magnet. Both a solenoid and a bar magnet have north and south poles, resulting in a similar pattern of magnetic field lines. A single straight current-carrying wire produces a different field pattern because it has no coil structure like a solenoid. A horseshoe magnet has a unique field shape due to its pole arrangement, different from the uniform field pattern of a solenoid. A flat sheet conductor does not exhibit the same magnetic field characteristics as a solenoid, as it lacks the coil shape and alignment of a solenoid's magnetic field.
Two 5-ohm resistors are placed in series and wired into a 100-V power supply. What current flows through this circuit?
- A. 2 A
- B. 10 A
- C. 20 A
- D. 50 A
Correct Answer: B
Rationale: In a series circuit, the total resistance is the sum of the individual resistances. Therefore, the total resistance in this circuit is 5 ohms + 5 ohms = 10 ohms. Using Ohm's Law (V = I R), we can find the current (I) by dividing the voltage (V) by the total resistance (R). I = V / R = 100 V / 10 ohms = 10 A.
Choice A (2 A) is incorrect because it does not account for the total resistance of the circuit. Choice C (20 A) and Choice D (50 A) are also incorrect as they provide values that are not consistent with the calculations based on the given values in the question.