A body undergoing `SHM` about the origin has its equation is given by `X=0.2 cos 5pit`. Find its average speed from `t=0 to t=0.7 sec`.

Explanation

` bar nu = ("Total distance")/("Total time")`
Here `x = 0.2 cos pi t`
Here `omega = 5 pi`
or `(2 pi)/(T) = 5 pi :. T = (2)/(5) = 0.4 sec`
Here `t = (n T)/(4) + t_(0)`
`t = n xx 0.1 + t_(0) or 0.7 = n xx 0.1 + t_(0)`
From this `n = 7 and t_(0) = 0`
But distance travelled in `T//4 is A = 0.2 xx 7 = 1//4 unit`
`:. "Total distance" = 0.2 xx 7 = 1.4 unit`
`:. bar nu = (1.4)/(0.7) = 2 unit`