🔍 Key Concepts

• Common mechanical root shapes used to retain turbine blades in disks (wheels) • Differences between integral mechanical locks (like shaped roots) and added fasteners (like bolts or rivets) • Why modern gas turbine rotor blades avoid extra hardware in high‑stress, high‑temperature areas

💭 Think About

• Look at which choices use a shaped root that locks into a matching slot in the turbine disk, rather than needing extra parts to hold it in place • Ask yourself: in a hot, high‑RPM turbine, which methods are most reliable for handling centrifugal force without small parts working loose? • Think about which methods you’ve actually seen in cross‑section diagrams of turbine wheels in your study materials

✅ Before You Answer

• Eliminate options that rely on separate small fasteners (like bolts or rivets) as the primary means of holding every blade in place • Confirm which root shapes (by name) are specifically identified in your text as standard turbine blade root designs • Make sure the pair you choose are both widely used as direct blade‑to‑disk mechanical interlocks, not just generic fastening methods