how should a researcher test the hypothesis that radiation from cell phones is significant enough to raise the temperature of water in a test tube
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HESI A2

HESI A2 Biology 2024

1. How should a researcher test the hypothesis that radiation from cell phones is significant enough to raise the temperature of water in a test tube?

Correct answer: A

Rationale: To test the hypothesis that radiation from cell phones raises the temperature of water in a test tube, the most appropriate method is to dial a cell phone next to a test tube of water, let it ring for a consistent two-minute interval, and record the temperature before and after. Choice A is correct because it provides a controlled approach to isolate the impact of the phone's radiation on the water temperature. Choices B, C, and D introduce additional variables that could confound the results. Choice B varies the duration of exposure, making it difficult to attribute temperature changes specifically to the radiation. Choice C introduces the factor of different cell phone brands, which could introduce variability not related to radiation. Choice D also varies exposure times and introduces the factor of multiple phone brands, making it harder to determine the direct impact of cell phone radiation on water temperature. Therefore, choice A is the most suitable option for this experiment.

2. Add: 3 1/8 + 1 1/4.

Correct answer: A

Rationale: To add mixed numbers, first add the fractions: 1/8 + 1/4 = 3/8. Then, add the whole numbers: 3 + 1 = 4. Therefore, 3 1/8 + 1 1/4 = 4 3/8. Choice B (4 1/2) is incorrect because the fractions were not added correctly, leading to an incorrect result. Choice C (4 3/4) is incorrect as it does not represent the correct sum of the two mixed numbers. Choice D (5 1/4) is incorrect as it provides a result that is higher than the correct sum of the mixed numbers.

3. Multiply 4/9 x 1 & 4/5 x 2/5.

Correct answer: C

Rationale: To multiply fractions, you multiply the numerators together and the denominators together. Calculating 4/9 x 1 & 4/5 x 2/5 gives you (4 x 1) / (9 x 1) & (4 x 2) / (5 x 5) = 4/9 & 8/25. Therefore, the correct answer is 8/25. Choices A, B, and D are incorrect because they do not result from the correct multiplication of the fractions provided.

4. A 10-kg object moving at 5 m/s has an impulse acted on it causing the velocity to change to 15 m/s. What was the impulse that was applied to the object?

Correct answer: D

Rationale: Impulse is the change in momentum of an object. The initial momentum is calculated as 10 kg × 5 m/s = 50 kg⋅m/s, and the final momentum is 10 kg × 15 m/s = 150 kg⋅m/s. The change in momentum (impulse) is 150 kg⋅m/s - 50 kg⋅m/s = 100 kg⋅m/s. Therefore, the impulse applied to the object is 100 kg⋅m/s. Choices A, B, and C are incorrect because they do not reflect the correct calculation of the impulse based on the change in momentum of the object.

5. What is the relationship between the tilt of the Earth and seasons as explained in the passage on Daylight Savings Time?

Correct answer: B

Rationale: The correct answer is B: 'The tilt of the Earth creates seasons.' The passage explains that the tilt of the Earth causes the different seasons by changing the amount of sunlight different regions receive. This tilt results in varying angles at which sunlight reaches different parts of the Earth, leading to the seasonal changes in temperature and daylight hours. Choice A is incorrect because the passage clearly states that the tilt of the Earth does have an effect on the seasons. Choice C is incorrect because the tilt of the Earth remains relatively constant throughout the year. Choice D is incorrect as the tilt of the Earth is not random but follows a consistent pattern.

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