Please answer the following questions:

Q4. A 50 cm steel rod (cylinder) used for reinforced concrete has a radius of 0.46 cm and it has a weight of 4.2 N. Calculate: a. the mass of the rod (2) b. the density of the rod (4) 0. suggest a reason why reinforced concrete might be used instead of concrete on its own. (2) Q5. Consider a light aluminium spring. A student hangs the spring in a vertical position and attaches to it a 50 9 mass. Secondly, the student attaches an additional 100 9 mass. a. What measurements should the student make in order to determine the extension caused by each of the two masses? (2) b. What does Hooke's law predict regarding how the two extensions will compare? (2) c. Explain in your scientic opinion, what is the most accurate way to determine spring constant of the spring. (2) Page 2