A fast pitch softball player does a "windmill" pitch moving her hand through a vertical circular arc to pitch a ball at 70mph. The 0.19 kg ball is 55 cm from the pivot point at her shoulder.

Just before the ball leaves her hand, what is its centripetal acceleration?

Explanation:

The hand throwing ball moves on a circular path having radius r = .55 m

mass of ball m = .19 kg

velocity v = 70 mph

= 70 x 1600 / 60 x 60

= 31.11 m /s

centripetal force

= mv² / r

= .19 x 31.11² / .55

= 334.34 N

the minimum amperage that the current in this wire would have to have so that its weight is completely supported by the magnetic force due to earth's field, assuming that no other forces except gravity act on it