HESI A2 Physics Quizlet

Correct Answer: A

Rationale: The correct answer is A: Its energy is halved. Kinetic energy is calculated using the formula KE = 0.5 * mass * velocity^2. Since kinetic energy is directly proportional to the square of velocity, if the speed drops from 60 mph to 30 mph, the kinetic energy will be reduced by a factor of 4 (30^2/60^2), which means it is halved. Summary: B: Its energy is doubled - Incorrect. Decreasing the speed from 60 mph to 30 mph reduces the kinetic energy, not double it. C: Its energy is quadrupled - Incorrect. Decreasing the speed results in a decrease in kinetic energy, not quadrupling it. D: Its energy is divided by four - Incorrect. The kinetic energy is reduced by a factor of 4, not divided by four.

Correct Answer: D

Rationale: To compress the spring from 40 cm to 30 cm, we calculate the change in length = 40 cm - 30 cm = 10 cm = 0.1 m. The force needed is given by Hooke's Law: F = k * x, where F is the force, k is the spring constant (20 N/m), and x is the change in length (0.1 m). Therefore, F = 20 N/m * 0.1 m = 2 N. Choice D (2 N) is correct because it correctly applies Hooke's Law. Choices A, B, and C are incorrect because they do not correctly calculate the force based on the given spring constant and change in length.

Correct Answer: B

Rationale: The correct answer is B: Decreases. When light travels from air into a denser medium like glass, it slows down due to the higher refractive index of the denser medium. This change in speed causes the light to bend or refract towards the normal line, demonstrating the phenomenon of refraction. The other choices are incorrect because light does not speed up when entering a denser medium (choice A), its speed is not constant (choice C), and it does not become unpredictable (choice D) - it follows the laws of physics governing refraction.

Correct Answer: A

Rationale: To calculate density, divide the mass by the volume. In this case, 24 g / 6 cm3 = 4 g/cm3. This is the correct answer (A) because density is expressed in units of mass per volume. Choice B is incorrect as it has the inverse units. Choices C and D are incorrect as they do not match the calculated value based on the given mass and volume.

Correct Answer: C

Rationale: The correct answer is C: Mechanical energy. Electric motors convert electrical energy into mechanical energy through the interaction of magnetic fields, which causes the motor to rotate and perform mechanical work. This process follows the principle of electromagnetic induction, where the electrical energy is transformed into kinetic energy. Choice A (Thermal energy) is incorrect as electric motors are designed to minimize heat generation. Choice B (Light) is incorrect as electric motors do not directly produce light. Choice D (Sound waves) is incorrect as electric motors do not primarily convert electrical energy into sound waves.