Nokea
What term describes the bending of waves around obstacles or through openings?
- A. Reflection
- B. Refraction
- C. Diffraction
- D. Absorption
Correct Answer: C
Rationale: The correct answer is C, Diffraction. Diffraction is the phenomenon that explains the bending of waves around obstacles or through openings. When waves encounter obstacles or pass through openings, they spread out and bend around them. Reflection (Choice A) involves waves bouncing back when they encounter a surface without bending, refraction (Choice B) is the bending of waves when passing from one medium to another due to a change in speed, and absorption (Choice D) is the process of a wave being taken in by a material rather than bending or bouncing.
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What is the formula to calculate work?
- A. Work = Force Distance
- B. Work = Mass Velocity
- C. Work = Power Time
- D. Work = Energy · Time
Correct Answer: A
Rationale: Work is defined as the product of the force applied to an object and the distance over which the force is applied. The formula to calculate work is represented by Work = Force Distance, where force is the applied force on an object and distance is the displacement over which the force is applied. Therefore, the correct formula to calculate work is Work = Force Distance.
Choice B, 'Work = Mass Velocity,' is incorrect because work involves force and distance, not mass and velocity. Choice C, 'Work = Power Time,' is incorrect because work is not directly calculated using power and time. Choice D, 'Work = Energy · Time,' is incorrect because work is not typically calculated by dividing energy by time; rather, it involves the product of force and distance.
Which factor most significantly affects the kinetic energy of an object?
- A. The object's mass
- B. The object's velocity
- C. The object's displacement
- D. The object's potential energy
Correct Answer: B
Rationale: Kinetic energy is directly proportional to the square of an object's velocity. This means that changes in velocity have a greater impact on the kinetic energy of an object compared to changes in mass, displacement, or potential energy. The mass of an object affects its kinetic energy, but the effect is linear, not squared like velocity. Displacement does not directly affect kinetic energy, as it is a measure of the change in position, not related to motion. Potential energy is a different form of energy and is not directly related to the kinetic energy of an object. Therefore, the velocity of an object has the most significant effect on its kinetic energy.
Why is biodiversity important for healthy ecosystems?
- A. Increases stability and resilience to disturbances
- B. Provides stability and resilience to disturbances
- C. Slows down nutrient cycling
- D. Reduces the number of decomposers
Correct Answer: B
Rationale: Biodiversity refers to the variety of living organisms in a particular area. A diverse ecosystem is better able to withstand and recover from disturbances such as natural disasters, climate change, or human impacts. This is because different species play unique roles in the ecosystem, and a higher level of biodiversity means there are more species available to fulfill these roles. For example, if one species is negatively affected by a disturbance, other species may be able to compensate for its loss, maintaining the overall functioning of the ecosystem. Therefore, biodiversity provides stability and resilience to disturbances, making ecosystems healthier and more sustainable. Choice A is incorrect because biodiversity doesn't increase competition for resources but rather helps in maintaining a balance within the ecosystem. Choice C is incorrect as biodiversity does not slow down nutrient cycling; in fact, it enhances nutrient cycling by ensuring a variety of species involved in the process. Choice D is incorrect as biodiversity does not reduce the number of decomposers but instead supports a diverse community of decomposers that are essential for nutrient recycling in ecosystems.
What type of force opposes the motion of an object moving through a fluid (liquid or gas)?
- A. Gravitational force
- B. Tension force
- C. Viscous force
- D. Magnetic force
Correct Answer: C
Rationale: When an object moves through a fluid, it experiences resistance due to the viscosity of the fluid. This resistance is known as the viscous force, which opposes the motion of the object. Gravitational force is the force of attraction between two objects with mass, tension force is the force transmitted through a string, and magnetic force is the force exerted by magnets. In the context of an object moving through a fluid, the force opposing its motion is the viscous force because it resists the relative motion of the object through the fluid.
When a blockage forms in a coronary artery, reducing blood flow to the heart muscle, this condition is called:
- A. Atherosclerosis
- B. Myocardial infarction
- C. Angina pectoris
- D. Heart murmur
Correct Answer: B
Rationale: A myocardial infarction, commonly known as a heart attack, occurs when a blockage forms in a coronary artery, leading to reduced blood flow to the heart muscle. Atherosclerosis refers to the buildup of plaque in the arteries, which can lead to blockages but is not the name for this specific condition. Angina pectoris is chest pain or discomfort due to inadequate blood supply to the heart muscle, which is a precursor to a heart attack but not the name for this condition. A heart murmur is an abnormal sound heard during a heartbeat, often due to turbulent blood flow, and is not related to a blockage in a coronary artery.