How fast must a 2.5-g ping-pong ball move in order to have the same kinetic energy as a 145 g baseball moving at 38.0 m/s?

Kinetic energy = (1/2)*m*v^2.  So we have (1/2)*(145 g)*(37 m/s)^2 = (1/2)*(2.5 g)*(v^2).

Solve for v = 281.78 m/s {about 630 miles per hour}

Explanation:

close lines strong magnet less close weaker

see the picture for the vector

the magnitude of the vector by pythagorean theorem

r = √( (-10)^2 + (3)^2 ) = √109

magnitude = √109 units

the direction angle between vector and x-axis is

tan^(-1)(3/10) = 16.699

so the direction is approximately 16.7 degrees north of west