Correct Answer: D

Rationale: When two wires carry current in the same direction, they create magnetic fields that interact with each other. This interaction results in an attractive force between the wires due to the alignment of their magnetic fields. Choice A is incorrect because the force can be predicted based on the direction of the currents and the magnetic fields produced. Choice B is incorrect because when currents flow in the same direction, they do not repel each other. Choice C is incorrect because there is indeed a force present due to the interaction of magnetic fields, resulting in attraction between the wires.

Correct Answer: A

Rationale: The second law of thermodynamics asserts that the entropy of an isolated system (or the combined system and surroundings) will always increase in a spontaneous process, reflecting an increase in disorder. Therefore, the correct answer is that the total entropy of the system and surroundings increases. Choice B is incorrect because entropy always tends to increase in a spontaneous process, as dictated by the second law of thermodynamics. Choice C is incorrect as entropy typically increases in natural processes. Choice D is incorrect because the second law of thermodynamics states that the total entropy of the system and surroundings always increases in a spontaneous process.

Correct Answer: B

Rationale: When light travels from air into a denser medium like glass, its speed decreases. This is because the higher refractive index of the denser medium causes light to slow down as it propagates through the medium. Choice A is incorrect because the speed of light decreases in a denser medium. Choice C is incorrect because the speed of light changes when it enters a denser medium. Choice D is incorrect because the change in speed is predictable based on the refractive index of the medium.

Correct Answer: C

Rationale: The work done by Amanda pushing the lawnmower is calculated by multiplying the force applied (100 N) by the distance over which the force is applied (the total distance mowed). Since Amanda mows 20 rows, each measuring 30 meters, the total distance mowed is 20 rows x 30 meters/row = 600 meters. Therefore, the work done is 100 N x 600 m = 60,000 Nâ‹…m. Option A and B are incorrect as they do not account for the total distance mowed. Option D is incorrect as the work done can be accurately calculated based on the information provided.

Correct Answer: B

Rationale: The correct answer is B, the highest peak. At the highest peak of the roller coaster, the car reaches its maximum height above the ground. This point represents the car's greatest potential energy because it has the highest potential to do work due to its elevated position. The potential energy is directly proportional to the height of an object, so the highest point on the roller coaster track corresponds to the car's greatest potential energy. Choices A, C, and D are incorrect because potential energy is highest at the peak due to its elevated position, not at the start of the ride, the lowest trough, or the end of the ride.