Question 5. Our results support the idea that if left to freely oscillate, a system will vibrate at a natural frequency that depends on the system itself, not on the initial push or stimulus that we impart. Based on this reasoning, consider a beam made out of iron and an otherwise identical beam made out of aluminum. How should the natural frequency of vibration of these two beams compare

(b) In ideal condition we neglect mass of spring but in real springs mass of spring adds another factor to its time period.

since we are adding a factor of mass to the system, and frequency being inversely proportional to squared root of mass, we can come to a general conclusion that it effectively reduces the natural frequency .

Explanation:

kindly check the attachment for explanation.

i think the answer is a and b

i wish you luck