A $100\, m$ long train is moving with a uniform velocity of $45\, km/hr$. The time taken by the train to cross a bridge of length $1 \,km$ is………$s$

A particle travels half of the distance of a straight journey with a speed $6 \,m / s$. The remaining part of the distance is covered with speed $2 \,m / s$ for half of the time of remaining journey and with speed $4 \,m / s$ for the other half of time. The average speed of the particle is ……. $m / s$

A car covers $A B$ distance with first one-third at velocity $v _{1} ms ^{-1}$, second one-third at $v _{2} ms ^{-1}$ and last one-third at $v _{3} ms ^{-1}$. If $v _{3}=3 v _{1}, v _{2}=2 v _{1}$ and $v _{1}=11\,ms ^{-1}$ then the average velocity of the car is________ $ms ^{-1} .$

A particle moving in a straight line covers half the distance with speed of $3 \,m/s$. The other half of the distance is covered in two equal time intervals with speed of $4.5 \,m/s$ and $7.5 \,m/s$ respectively. The average speed of the particle during this motion is…… $\,m/s$

Give difference between average speed and average velocity.