A bullet fired into a fixed target loses half of its velocity after penetrating $3\, cm$. How much further it will penetrate before coming to rest assuming that it faces constant resistance to motion ?.......$cm$
A small electric car has a maximum constant acceleration of $1\,m / s ^2$, a maximum constant deceleration of $2\,m / s ^2$ and a maximum speed of $20\,m / s$. The amount of time it would take to drive this car $1\,km$ starting from rest and finishing at rest is $.........\,s$