HESI A2 Physics

Correct Answer: B

Rationale: The correct answer is B: The electromotive force induced by a changing magnetic field. Metal detectors work based on electromagnetic induction where a changing magnetic field induces an electric current in conductive materials like metals. This current generates a secondary magnetic field that is detected by the metal detector. This principle allows metal detectors to identify the presence of metal objects. A: The static presence of a permanent magnet is incorrect because metal detectors do not rely on the static presence of a permanent magnet but rather on inducing electric currents in metals. C: The high electrical conductivity of most metals is incorrect because while it is true that metals are good conductors of electricity, the principle behind metal detectors is based on electromagnetic induction, not on electrical conductivity. D: The unique thermal signature of metallic objects is incorrect because metal detectors do not detect metals based on their thermal properties but rather on the interaction of metals with changing magnetic fields.

Correct Answer: B

Rationale: The continuity equation in fluid dynamics states that the mass entering a system must equal the mass exiting the system for mass to be conserved. This is why the correct answer is B: Mass. Momentum (A) is related to the motion of fluids, not mass conservation. Energy (C) is related to the total energy of the system, not specifically mass conservation. Angular momentum (D) is related to rotational motion, not mass conservation. Therefore, the correct answer is B.

Correct Answer: D

Rationale: To calculate work, we use the formula W = F*d, where W is work, F is force, and d is distance. In this case, the force is 15 N and the distance is 3 m. So, W = 15 N * 3 m = 45 N⋅m. Therefore, the correct answer is D. Choice A is incorrect as it incorrectly calculates work by dividing force by distance. Choice B is incorrect as it only provides the correct unit for work, not the actual calculation. Choice C is incorrect as it incorrectly multiplies force and distance to get the wrong result.

Correct Answer: D

Rationale: The correct answer is D. Displacement is the change in position from the starting point to the endpoint, regardless of the path taken. In this case, traveling 500 miles northeast and then 500 miles southwest cancels out the movement, resulting in a displacement of 0 miles. However, the distance traveled is the total distance covered, which is 1,000 miles in this case. Therefore, option D correctly states that the displacement is 0 miles, and the distance traveled is 1,000 miles. Option A is incorrect because the distance traveled is not 0 miles. Option B is incorrect as the displacement is 0 miles. Option C is incorrect as both displacement and distance traveled are not 0 miles.

Correct Answer: A

Rationale: The correct answer is A: 5 miles per hour due southwest. A vector quantity has both magnitude and direction, which is represented by the speed (5 miles per hour) and the direction (southwest). This choice clearly indicates both aspects. Explanation for why the other choices are incorrect: - B: 5 miles per hour: This choice only provides the magnitude of the quantity (speed) without indicating any direction. - C: 5 miles: This choice only provides the magnitude (distance) without any indication of direction. - D: None of the above: This choice dismisses all options without providing the correct representation of a vector quantity with both magnitude and direction.