HESI A2 Physics

Correct Answer: D

Rationale: The correct answer is D: Cannot be created or destroyed. According to the law of conservation of energy, energy can neither be created nor destroyed, but only transformed from one form to another. This principle is a fundamental law of physics known as the first law of thermodynamics. Any process involving energy transfer must adhere to this law. Choices A, B, and C are incorrect because they contradict this fundamental principle. Energy cannot be created out of nothing or disappear completely; it can only change forms.

Correct Answer: A

Rationale: To calculate the magnitude of the resulting force, we use Coulomb's Law: F = k * |q1 * q2| / r^2, where k is the electrostatic constant (8.99 x 10^9 N m^2/C^2), q1 and q2 are the charges, and r is the distance between them. Plugging in the values: F = (8.99 x 10^9) * |4 x 10^-6 * 2 x 10^-6| / 1^2 = 0.072 N. However, the question asks for the magnitude, so the answer should be 0.072 N, which corresponds to choice B. The other choices are incorrect because they do not correctly calculate the force using Coulomb's Law or misinterpret the question.

Correct Answer: B

Rationale: To find the frequency, we use the formula: speed = wavelength x frequency. Given speed = 12 m/s and wavelength = 2 m, we can rearrange the formula to solve for frequency: frequency = speed / wavelength = 12 m/s / 2 m = 6 Hz. Choice A (38.4 Hz) is incorrect as it would be the frequency if the wavelength was 0.3125 m, not 2 m. Choice C (4.6 Hz) and D (3.75 Hz) are also incorrect as they do not match the calculated frequency of 6 Hz based on the given values.

Correct Answer: C

Rationale: To find the image distance using the mirror formula (1/f = 1/v + 1/u), we first need to calculate the object distance (u). Given the object distance (u) is 20 cm, and the focal length (f) is 10 cm, we can substitute these values into the formula to find the image distance (v). Solving for v, we get v = 60 cm. Therefore, the correct answer is C: 60 cm. Choice A (20 cm) is incorrect as the image distance is not equal to the object distance when using a concave mirror. Choice B (40 cm) is incorrect as it does not account for the focal length of the mirror. Choice D (75 cm) is incorrect as it is not the result of the correct calculation using the mirror formula.

Correct Answer: C

Rationale: The correct answer is C (24 units). When you double the mass of both objects, the gravitational force between them increases by a factor of 4 (2 times 2). Therefore, the new force of attraction would be 12 units x 4 = 24 units. Choice A (3 units) and B (6 units) are incorrect because they do not account for the increase in mass. Choice D (48 units) is incorrect as it overestimates the effect of doubling the mass on the gravitational force.