Nokea
Which of the following substances has the highest density?
- A. Mist
- B. Water
- C. Steam
- D. Ice
Correct Answer: B
Rationale: Water has the highest density among the options provided. Density is a measure of mass per unit volume. In this case, water in its liquid form is denser than mist, steam, and ice. Ice has a lower density than water because its crystalline structure causes it to be less dense. Mist and steam are forms of water vapor, which are much less dense than liquid water. Therefore, the correct answer is water (choice B).
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When a junked car is compacted, which statement is true?
- A. Its mass increases.
- B. Its mass decreases.
- C. Its density increases.
- D. Its density decreases.
Correct Answer: C
Rationale: When a junked car is compacted, its volume decreases while its mass remains the same. As a result, the car's density increases because density is mass divided by volume. Choice A is incorrect because the mass of the car remains the same. Choice B is incorrect because the mass does not decrease. Choice D is incorrect because the density increases as the volume decreases, not decreases.
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:
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.
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.
The drag force (F_d) experienced by an object moving through a fluid depends on:
- A. Object's shape and size only
- B. Fluid properties and object velocity
- C. Depth of submersion only
- D. Buoyant force acting on the object
Correct Answer: B
Rationale: The drag force experienced by an object moving through a fluid depends on multiple factors, including the object's shape, size, velocity, and the fluid's properties such as viscosity and density. Choices A, C, and D are incorrect because drag force is not solely determined by the object's shape and size, depth of submersion, or buoyant force acting on the object. The primary factors affecting drag force are the fluid properties and the object's velocity. Therefore, the correct answer is B.