Читать книгу Essentials of MRI Safety - Donald W. McRobbie - Страница 81

We can estimate the velocity of ferromagnetic projectiles from the basic laws of mechanics (Figure 2.20). One non‐intuitive feature of projectile velocities is that they are broadly independent of the mass of the object. For example, if the densities of two objects are equal, then the translational force will scale with the mass, but acceleration scales with its inverse. Provided objects are the same shape (rather than size) and made of the same material, they will fly in equally fast with velocities of tens of meters per second‐ in under half a second for a given magnet!

Figure 2.20 Predicted projectile velocity for the objects and magnets in Figure 2.19 saturating at 1.6 and 0.5 T.