Nokea
What is the SI unit of measurement for acceleration?
- A. Meters per second (m/s)
- B. Newton (N)
- C. Meters (m)
- D. Meters per second squared (m/s²)
Correct Answer: D
Rationale: The SI unit of measurement for acceleration is meters per second squared (m/s²). Acceleration is defined as the rate of change of velocity over time. It is a vector quantity with dimensions of length per time squared. Meters per second squared (m/s²) represents the change in velocity (meters per second) over a specific time interval (seconds) squared. Choice A, meters per second (m/s), represents velocity, not acceleration. Choice B, Newton (N), is the unit of force. Choice C, Meters (m), represents only distance, not acceleration. Therefore, the correct unit for acceleration is meters per second squared (m/s²).
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What is the process by which a solid changes directly into a liquid?
- A. Melting
- B. Condensation
- C. Sublimation
- D. Deposition
Correct Answer: A
Rationale: The correct answer is A: Melting. Melting is the process through which a solid substance changes directly into a liquid. Choice B, Condensation, is the transition from gas to liquid. Choice C, Sublimation, refers to the direct change from solid to gas. Choice D, Deposition, is the direct transition from gas to solid, not from solid to liquid as in the question.
Which element has the same number of protons and neutrons?
- A. Carbon (C)
- B. Oxygen (O)
- C. Lithium (Li)
- D. Helium (He)
Correct Answer: D
Rationale: The correct answer is Helium (He). Helium has an atomic number of 2, meaning it has 2 protons. It also has 2 neutrons, which gives it a total mass number of 4. Therefore, Helium is an example of an element with an equal number of protons and neutrons.
Choice A (Carbon) has 6 protons and usually has more neutrons than protons. Choice B (Oxygen) has 8 protons and 8 neutrons, so the numbers are not equal. Choice C (Lithium) has 3 protons and usually has more neutrons than protons, so it does not fit the criteria of having the same number of protons and neutrons.
Which hormone stimulates the release of pancreatic enzymes and bile?
- A. Gastrin
- B. Insulin
- C. Cholecystokinin (CCK)
- D. Glucagon
Correct Answer: C
Rationale: Cholecystokinin (CCK) is the correct answer. It is the hormone that stimulates the release of pancreatic enzymes and bile. CCK is released by the small intestine in response to the presence of fats and proteins in the duodenum, triggering the release of digestive enzymes and bile to aid in the digestion of fats and proteins. Gastrin (Choice A) primarily stimulates gastric acid secretion, not the release of pancreatic enzymes and bile. Insulin (Choice B) regulates blood sugar levels by promoting glucose uptake. Glucagon (Choice D) raises blood glucose levels by stimulating the breakdown of glycogen in the liver.
What is the half-life of a radioactive isotope, and how does it relate to its decay rate?
- A. The time it takes for half of the initial sample to decay.
- B. The time it takes for all of the sample to decay.
- C. The rate at which new isotopes are created.
- D. The energy released during decay.
Correct Answer: A
Rationale: The half-life of a radioactive isotope is the time it takes for half of the initial sample to decay. After one half-life, half of the radioactive atoms have decayed. The decay rate, however, refers to the rate at which radioactive atoms decay, which is not directly related to the half-life. Choice B is incorrect because it does not correctly define the half-life. Choice C is incorrect as it refers to the creation of new isotopes, not the decay process. Choice D is incorrect as it describes the energy released during decay, which is not the same as the concept of half-life.
A pendulum swings back and forth. What type of energy conversion occurs during its motion?
- A. Potential energy to kinetic energy and vice versa
- B. Thermal energy to mechanical energy and vice versa
- C. Chemical energy to electrical energy and vice versa
- D. Nuclear energy to radiant energy and vice versa
Correct Answer: A
Rationale: As the pendulum swings back and forth, it undergoes a continuous conversion between potential energy (at the highest point of the swing) and kinetic energy (at the lowest point of the swing). At the highest point, the pendulum has maximum potential energy due to its height above the ground. As it swings down, this potential energy is converted into kinetic energy, which is the energy of motion. At the lowest point of the swing, the pendulum has maximum kinetic energy and minimal potential energy. The process repeats as the pendulum swings back in the opposite direction, demonstrating the conversion between potential and kinetic energy. Choices B, C, and D are incorrect because the energy conversion in a swinging pendulum primarily involves changes between potential and kinetic energy, not thermal, chemical, electrical, nuclear, or radiant energy.