The branch of Physics which deals with the motion of objects while taking into consideration the cause of motion is

An electron moving with a velocity of $5 \times 10^{4} \, ms^{-1}$ enters into a uniform electric field and acquires a uniform acceleration of $10^{4} \, ms^{-2}$ in the direction of its initial motion.
$(i)$ Calculate the time in which the electron would acquire a velocity double of its initial velocity.
$(ii)$ How much distance the electron would cover in this time?

If the average velocity of a body is equal to the mean of its initial velocity and final velocity,then the acceleration of the body is

$(a)$ What is acceleration? Write its $SI$ unit.
$(b)$ Draw velocity-time graphs for an object having:
$(i)$ Uniformly accelerated velocity.
$(ii)$ Uniformly retarded velocity.

$A$ cyclist travels a distance of $4\, km$ from $P$ to $Q$ and then moves a distance of $3\, km$ at a right angle to $PQ$. Find his resultant displacement graphically.

$A$ scooter starts from rest and moves in a straight line with a constant acceleration,covering a distance of $64 \, m$ in $4 \, s$.
$(i)$ Calculate its acceleration and its final velocity.
$(ii)$ At what time had the scooter covered half the total distance?