Explain the following type of motion with one example of each

$(i)$ Acceleration is positive

$(ii)$ Acceleration is negative

$(iii)$ Acceleration is zero.

The brakes applied to a car produce an acceleration of $6\, m s ^{-2}$ in the opposite direction of motion. If the car takes $2\, s$ to stop after the application of the brakes, calculate the distance it travels during this time.

The velocity$-$time graph of an ascending passenger lift is as in the figure shown below

$(i)$ Identify the kind of motion of lift represented by lines $OA$ and $BC$.

$(ii)$ Calculate the acceleration of the lift

$(a)$ During the first two seconds.

$(b)$ Between the $3^ {r d}$ and $10^ {t h}$ second.

$(c)$ During the last two seconds.

For the motion on a straight line path with constant acceleration the ratio of the maqnitude of the displacement to the distance covered is

The average time taken by a normal person to react to an emergency is one$-$fifteenth of a second and is called the 'reaction time'. If a bus is moving with a velocity of $60\, km h^{-1}$ and its driver sees a child running across the road, how much distance would. the bus had moved before he could press the brakes ? The reaction time of the people increases when they are intoxicated. How much distance had the bus moved if the reaction time of the driver were $\frac{1}{2}\, s$ under the influence of alcohol ?