[填空题]
A softball having a mass );t-i bxr/lzeka, bkb5 s.;rp;qle +xof 0.25 kg is pitchre h eahd */4x;q1)mbhed at By the time it reaches the plate, it may have slowed by 11qax d/4h )*b e;mrheh0%. Neglecting gravity, estimate the average force of air resistance during a pitch, if the distance between the plate and the pitcher is about 15 m. N
