[填空题]
Peter is playing on a swing during a school lunch break. Tz+l4x3 i;tgjghe height of the5x -nz r9rbg:n firstnrnzb-g5x :r9 swing was 2 m and every subsequent swing was 84 % of the previous one. Peter's friend, Ronald, gives him a push whenever the height falls below 1 m.
1.Find the height of the third swing.
we find $u_3$ ≈ m.
2.Find the number of swings before Ronald gives Peter a push.
Hence the swing needs a push after swings.
3.Calculate the total height of swings if Peter is left to swing until coming
to rest.
$S_∞$= m.
