Nokea
When is work done on an object?
- A. Only when the object's velocity changes
- B. Only when a force is applied to the object
- C. Whenever there is a force exerted on the object causing displacement
- D. Only when the object is lifted vertically
Correct Answer: C
Rationale: Work is done on an object whenever a force causes displacement in the object's position. According to the work-energy principle, work is calculated as the force applied multiplied by the distance the object moves in the direction of the force. Therefore, work can occur whenever there is a force exerted on the object resulting in displacement, regardless of whether the object's velocity changes or it is lifted vertically. Choice A is incorrect because work can be done even without a change in velocity. Choice B is incorrect as work requires both force and displacement, not just the application of force. Choice D is incorrect because work is not limited to vertical lifting; it can happen in any direction as long as there is a force causing displacement.
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Which of the following is an example of a chemical change?
- A. Dissolving sugar in water
- B. Boiling water
- C. Rusting iron
- D. Crushing ice
Correct Answer: C
Rationale: Rusting iron is an example of a chemical change because it involves a chemical reaction where iron reacts with oxygen in the presence of water to form iron oxide (rust). This reaction results in a change in the chemical composition of the iron, unlike dissolving sugar in water, boiling water, or crushing ice, which are physical changes. Dissolving sugar in water is a physical change as sugar molecules remain unchanged but disperse in water. Boiling water is also a physical change as water changes its state from liquid to gas due to heat. Crushing ice is a physical change as the solid ice changes its physical form without altering its chemical composition.
Which bones are included in the axial skeleton?
- A. Head, neck, and trunk
- B. Arms and legs
- C. Hands and feet
- D. All of the above
Correct Answer: A
Rationale: The correct answer is A: Head, neck, and trunk. The axial skeleton comprises bones located in the head, neck, and trunk region, such as the skull, vertebral column, and rib cage. These bones provide structural support and protect vital organs like the brain, spinal cord, and heart. Choices B and C are incorrect because arms, legs, hands, and feet are part of the appendicular skeleton, not the axial skeleton. The appendicular skeleton is responsible for movement, manipulation, and mobility, while the axial skeleton primarily provides central support and protection for essential organs.
When unpolarized light passes through a polarizing filter, the intensity of the transmitted light is:
- A. Completely absorbed
- B. Reduced by half
- C. Unaffected
- D. Doubled
Correct Answer: B
Rationale: When unpolarized light passes through a polarizing filter, the filter only allows light waves oscillating in a specific direction to pass through while blocking light waves oscillating in other directions. Since unpolarized light consists of light waves oscillating in all possible directions, when it passes through a polarizing filter, only half of the light waves (those oscillating in the direction allowed by the filter) are transmitted. As a result, the intensity of the transmitted light is reduced by half. Choice A is incorrect because the light is not completely absorbed; choice C is incorrect because the polarizing filter affects the transmitted light; and choice D is incorrect because the intensity does not double, but rather decreases by half due to the selective transmission of light waves in a specific direction by the polarizing filter.
What is the definition of work in physics?
- A. Force applied to an object at rest
- B. Force exerted by an object in motion
- C. Transfer of energy through motion along a direction
- D. Measure of an object's potential energy
Correct Answer: C
Rationale: In physics, work is defined as the transfer of energy through motion along a direction. When a force is applied to an object, and the object moves in the direction of the force, work is done on the object. The work done is calculated as the force applied multiplied by the distance the object moves in the direction of the force. Choices A and B do not fully capture the essence of work, as work is about energy transfer through motion, not merely applying force to objects at rest or in motion. Choice D is incorrect as work is not a measure of an object's potential energy; rather, it is the transfer of energy through motion.
When referring to blood vessel walls, the term 'atherosclerosis' describes:
- A. The abnormal buildup of plaque within the arterial walls.
- B. The inflammation of the inner lining of blood vessels.
- C. The dilation and weakening of a blood vessel wall (aneurysm).
- D. The normal process of blood vessel wall thickening with age.
Correct Answer: A
Rationale: The correct answer is A: 'The abnormal buildup of plaque within the arterial walls.' Atherosclerosis is the process where plaque, consisting of fat, cholesterol, calcium, and other substances, accumulates within the arteries. This buildup can lead to the hardening and narrowing of arteries, reducing blood flow and potentially causing severe health issues like heart attacks and strokes. Choice B is incorrect because inflammation of the inner lining of blood vessels is known as vasculitis, not atherosclerosis. Choice C is incorrect as it describes an aneurysm, which is a dilation and weakening of a blood vessel wall, not atherosclerosis. Choice D is incorrect as it describes arteriosclerosis, a process of blood vessel wall thickening with age, which is different from atherosclerosis.