Question

why do engineers choose steel for bridges and roller coasters? steel is light and floats in water steel has irregular atoms that break apart easily steel is strong and holds its shape under pressure steel is soft and easy to stretch question 2 what makes aluminum a useful material for outdoor structures?

Explanation:

Steel is an alloy known for its high strength - to - weight ratio. Bridges and roller coasters need materials that can withstand significant forces (such as the weight of vehicles on a bridge or the forces experienced during a roller - coaster ride).

• Option 1: Steel has a density of about \(7.85\ g/cm^{3}\), which is much higher than water (\(1\ g/cm^{3}\)), so it does not float.
• Option 2: Steel has a regular crystalline structure (in the form of ferrite, austenite, etc. depending on the type of steel). It is not composed of irregular atoms that break apart easily. In fact, its atomic structure gives it strength.
• Option 3: Steel has a high tensile strength (the ability to resist being pulled apart) and compressive strength (the ability to resist being pushed together). This property allows it to hold its shape under the various pressures (dead load, live load for bridges; gravitational and inertial forces for roller coasters) it will encounter.
• Option 4: Steel is not soft. While there are different grades of steel with varying hardness levels, in general, it is a hard material. For example, high - carbon steel is very hard and is used in applications where wear resistance is important.

Answer:

Steel is strong and holds its shape under pressure.