which vehicle has the greatest momentum

HESI A2

HESI A2 Physics

1. Which vehicle has the greatest momentum?

A. A 9,000-kg railroad car traveling at 3 m/s
B. A 2,000-kg automobile traveling at 24 m/s
C. A 1,500-kg MINI Coupe traveling at 29 m/s
D. A 500-kg glider traveling at 89 m/s

Correct answer: D

Rationale: The momentum of an object is calculated by multiplying its mass by its velocity. The momentum formula is p = m × v, where p is momentum, m is mass, and v is velocity. Comparing the momentum of each vehicle: A: 9,000 kg × 3 m/s = 27,000 kg·m/s B: 2,000 kg × 24 m/s = 48,000 kg·m/s C: 1,500 kg × 29 m/s = 43,500 kg·m/s D: 500 kg × 89 m/s = 44,500 kg·m/s. Therefore, the glider (500-kg) traveling at 89 m/s has the greatest momentum of 44,500 kg·m/s, making it the correct choice. Options A, B, and C have lower momentum values compared to option D, proving that the 500-kg glider traveling at 89 m/s has the highest momentum among the given vehicles.

2. What is the electric field inside a hollow conductor with a net charge?

A. Remains constant
B. Decreases
C. Zero
D. Becomes unpredictable

Correct answer: C

Rationale: The correct answer is C: Zero. According to Gauss’s Law, the electric field inside a hollow conductor (a conductor with no charge inside but a net charge on its surface) is zero. The charges reside on the outer surface of the conductor, causing the electric field inside to cancel out. Choices A, B, and D are incorrect because the electric field inside a hollow conductor with a net charge is not constant, does not decrease, and does not become unpredictable; it is zero due to the distribution of charges on its surface.

3. Ocean waves build during a storm until there is a vertical distance from the high point to the low point of 6 meters and a horizontal distance of 9 meters between adjacent crests. The waves hit the shore every 5 seconds. What is the speed of the waves?

A. 1.2 m/s
B. 1.8 m/s
C. 2.0 m/s
D. 2.4 m/s

Correct answer: B

Rationale: To find the speed of the waves, we use the formula: speed = wavelength / period. The wavelength is the horizontal distance between adjacent crests, which is 9 meters in this case. The period is the time it takes for one wave to pass a fixed point, given as 5 seconds. Therefore, speed = 9 meters / 5 seconds = 1.8 m/s. Choice A (1.2 m/s) is incorrect because it miscalculates the speed. Choice C (2.0 m/s) and Choice D (2.4 m/s) are incorrect as they do not correctly calculate the speed using the provided data.

4. As the frequency of a sound wave increases, what else is true?

A. Its wavelength decreases.
B. Its wavelength increases.
C. Its amplitude decreases.
D. Its amplitude increases.

Correct answer: A

Rationale: The correct answer is A: 'Its wavelength decreases.' The frequency and wavelength of a sound wave are inversely proportional. As the frequency of a sound wave increases (more oscillations per second), its wavelength decreases. This relationship is described by the formula: Speed of Sound = Frequency x Wavelength. Therefore, to maintain the speed of sound constant, when the frequency increases, the wavelength must decrease. Choices B, C, and D are incorrect because an increase in frequency does not lead to an increase in wavelength or changes in amplitude.