A child is swinging a swing. Minimum and maximum heights fo swing from the earth's surface are 0.75 m and 2 m respectively. The maximum velocity of this swing is

Explanation

From energy conservation,
Gain in kinetic energy =loss in potential energy
`implies (1//2)mv_(max)^(2)=mg(H_(2)-H_(1))`
Here, `H_(1)`= minimum height of the swing from earth's surface =0.75 m
`H_(2)`= maximum height of swing from earth's surface =2 m
`:. (1//2)mv_(max)^(2)=mg(2-0.75)`
or `" " v_(max)=sqrt(2xx10xx1.25)=sqrt(25)=5 ms^(-1)`