Nokea
At the peak of a baseball's trajectory, which of the following forces is acting on the ball?
- A. Only gravitational force
- B. Only the force of air resistance
- C. Both gravitational force and the force of air resistance
- D. Neither gravitational force nor the force of air resistance
Correct Answer: A
Rationale: At the peak of a baseball's trajectory, the ball momentarily stops moving upwards before it starts to fall back down. During this moment of temporary rest, the only force acting on the ball is the gravitational force pulling it downward towards the Earth. The force of air resistance is negligible at this point because the ball is momentarily stationary, and air resistance requires motion to be significant. Therefore, the correct answer is that only the gravitational force is acting on the ball at the peak of its trajectory. Choices B, C, and D are incorrect because air resistance does not have a significant effect when the ball is at its peak and momentarily stationary.
You may also like to solve these questions
What controls the involuntary, rhythmic contractions of the heart muscle?
- A. Lungs
- B. Brain
- C. Spinal cord
- D. Sinoatrial node (located within the heart)
Correct Answer: D
Rationale: The correct answer is D: Sinoatrial node (located within the heart). The involuntary, rhythmic contractions of the heart muscle are controlled by a specialized group of cells located within the heart called the sinoatrial node (SA node). The SA node acts as the heart's natural pacemaker, producing electrical impulses that regulate the heart rate and synchronize the contractions of the heart muscle. Choices A, B, and C (Lungs, Brain, Spinal cord) are not responsible for directly influencing the rhythmic contractions of the heart muscle.
Which part of the spinal cord is responsible for transmitting sensory information from the body to the brain?
- A. Dorsal root
- B. Ventral root
- C. Gray matter
- D. White matter
Correct Answer: A
Rationale: The correct answer is the dorsal root. The dorsal root of the spinal cord contains sensory nerve fibers that transmit sensory information from the body to the brain. This information includes touch, pain, temperature, and proprioception. The ventral root, on the other hand, contains motor nerve fibers responsible for carrying signals from the brain to the muscles and glands, controlling movement and glandular functions. Gray matter, consisting mainly of cell bodies, is involved in processing and integrating sensory and motor information within the spinal cord. White matter is primarily composed of myelinated axons that facilitate communication between different regions of the nervous system, allowing signals to travel efficiently within the spinal cord and between the brain and other parts of the body. Therefore, the dorsal root is specifically associated with transmitting sensory information, making it the correct answer in this context.
Which epithelial tissue type is the outermost layer of your skin an example of?
- A. Simple cuboidal
- B. Stratified squamous
- C. Simple columnar
- D. Stratified columnar
Correct Answer: B
Rationale: The outermost layer of the skin, known as the epidermis, is composed of stratified squamous epithelial tissue. This type of tissue is well-suited for protection against mechanical stress and dehydration, making it ideal for the skin's barrier function. Simple cuboidal (Choice A) epithelial tissue is found in areas where secretion and absorption occur, such as kidney tubules. Simple columnar (Choice C) epithelial tissue lines the digestive tract, providing a large surface area for absorption. Stratified columnar (Choice D) epithelial tissue is less common and is found in limited regions like parts of the male urethra and ducts of some glands, but not in the outermost layer of the skin.
Which muscle type is characterized by a combination of voluntary and involuntary control, is striated, and is responsible for pumping blood throughout the circulatory system?
- A. Skeletal muscle
- B. Smooth muscle
- C. Cardiac muscle
- D. Connective tissue
Correct Answer: C
Rationale: The correct answer is C, Cardiac muscle. Cardiac muscle is characterized by a combination of voluntary and involuntary control, is striated, and is responsible for pumping blood throughout the circulatory system. Skeletal muscle is primarily under voluntary control, smooth muscle is primarily under involuntary control, and connective tissue is not a muscle type, but rather provides support and structure to the body.
What property of a substance refers to its ability to undergo a chemical change and form new substances?
- A. Density
- B. Mass
- C. Reactivity
- D. Volume
Correct Answer: C
Rationale: Reactivity is the property of a substance that describes its ability to undergo a chemical change and form new substances. Density (A), mass (B), and volume (D) are physical properties of a substance and do not directly relate to its ability to undergo chemical changes. Density is the measure of how much mass is contained in a given volume, mass is the amount of matter in an object, and volume is the amount of space an object occupies. Therefore, reactivity (C) is the correct answer as it specifically addresses the substance's ability to undergo chemical changes.