Q. A proton moves perpendicularly to a uniform magnetic ?eld B with a speed of 1.9 × 10 ^7 m/s and experiences an acceleration of 8 × 10 12 m/s 2 in the positive x direction when its velocity is in the positive z direction. The mass of a proton is 1.673 × 10 -27 kg. Find the magnitude of the ?eld.
Q. A 7.80-g bullet moving at 570 m/s penetrates a tree trunk to a depth of 5.6 cm.
Use work and energy considerations to find the average frictional force that stops the bullet.