$A$ train $100 \, m$ long is moving with a velocity of $60 \, km/h$. Find the time it takes to cross a bridge $1 \, km$ long.

Define velocity.

The following figure is the speed-time graph for a rocket from the moment when the fuel starts to burn,i.e.,at time $t=0$.
$(a)$ State the acceleration of the rocket at $t=0$.
$(b)$ State what happens to the acceleration of the rocket between $t=5 \, s$ and $t=60 \, s$.
$(c)$ Calculate the acceleration of the rocket at $t=80 \, s$. Give a reason for your answer.
$(d)$ The total mass of the rocket at $t=80 \, s$ is $1.6 \times 10^{6} \, kg$. Calculate the resultant force on the rocket at this time. Give a reason for your answer.

An object starts a linear motion with velocity $u$ and with uniform acceleration $a$,it acquires a velocity $v$ in time $t$.
$(a)$ Draw its velocity-time graph.
$(b)$ Obtain the first equation of motion,$v = u + at$,for the velocity-time relation by using the velocity-time graph.
$(c)$ $A$ body moving with a velocity of $2 \, m s^{-1}$ acquires a velocity of $10 \, m s^{-1}$ in $5 \, s$. Find its acceleration.

There are $5$ houses on a street,$A, B, C, D$ and $E$. For all cases,assume that positions to the right are positive.
$(i)$ Draw a frame of reference with house $A$ as the origin and the positions of houses $B, C, D$ and $E$.
$(ii)$ You live in house $C$. What is your position relative to house $E$?
$(iii)$ What are the positions of houses $A$ and $D$,if house $B$ is taken as the reference point?

Two cars $A$ and $B$ have their displacement-time graph as given below. Which car has a greater velocity?