The radius vector of a particle varies with time t as `vecr=vecbt(1-alpha t)`where `vecb`is a constant vector and a is a positive factor . Find the time interval `Delta t ` taken by the particle to return to the initial point

Explanation

`vecr=vecbt(1-alpha t)`
For initial point , `vecr=0,vecb=t(1-alphat)=0`
`t=0"and" t=1/alpha` Hence,` Deltat=1/alpha `