Q. One electron collides elastically with a second electron initially at rest. After the collision, the radii of their trajectories are 1 cm and 2.4 cm. The trajectories are perpendicular to a uniform magnetic ?eld of magnitude 44 mT. Determine the energy (in keV) of the incident electron.
Q. A steel wire of mass 0.400 kg and length 0.640 m supports a 102-kg block. The wire is struck exactly at its midpoint causing a small displacement. How long does it take the peak of this displacement to reach the top of the wire?