Afootball quarterback is moving straight backward at a speed of 1.91 m/s when he throws a pass to a player 16.1 m straight downfield. the ball is thrown at an angle of 37.3° relative to the ground and is caught at the same height as it is released. what is the initial velocity of the ball relative to the quarterback? (assume downfield to be in the +x-direction. enter the magnitude in m/s and the direction in degrees counterclockwise from the +x-axis.)

An alpha particle with kinetic energy 12.5 mev makes a collision with lead nucleus, but it is not "aimed" at the center of the lead nucleus, and has an initial nonzero angular momentum (with respect to the stationary lead nucleus) of magnitude l = p0 b, where p0 is the magnitude of the initial momentum of the alpha particle and b=1.40×10−12 m. (assume that the lead nucleus remains stationary and that it may be treated as a point charge. the atomic number of lead is 82. the alpha particle is a helium nucleus, with atomic number 2.) what is the distance of closest approach?