The position of an object moving along the x-axis is given by, \(x=a+bt^2\), where \(a=8.5 \) m, \(b=2.5\) ms^–2, and \(t\) is measured in seconds. Its velocity at \(t=2.0\) s will be:
1. \(13\) m/s
2. \(17\) m/s
3. \(10\) m/s
4. \(0\)

The position-time graph for a free-falling object is:

A train is moving in the north direction with a speed of \(54\) ${\mathrm{kmh}}^{-1}$. The velocity of a monkey running on the roof of the train against its motion (with a velocity of \(18\) ${\mathrm{kmh}}^{-1}$ with respect to the train) as observed by a man standing on the ground is:
1. \(40\) ms^-1
2. \(0\)
3. \(-5\) ms^-1
4. \(10\) ms^-1

Two parallel rail tracks run north-south. Train A moves north with a speed of 54 ${\mathrm{kmh}}^{-1}$, and train B moves south with a speed of 90 ${\mathrm{kmh}}^{-1}$. The magnitude of the velocity of B with respect to A is:

1.  40 ${\mathrm{ms}}^{-1}$

2.  0 ${\mathrm{ms}}^{-1}$

3.  25 ${\mathrm{ms}}^{-1}$

4.  15 ${\mathrm{ms}}^{-1}$

A train is moving in south with a speed of 90 ${\mathrm{kmh}}^{-1}$. The velocity of ground with respect to the train is:

1.  0 ${\mathrm{ms}}^{-1}$

2.  -25 ${\mathrm{ms}}^{-1}$

3.  25 ${\mathrm{ms}}^{-1}$

4.  -40 ${\mathrm{ms}}^{-1}$

Galileo’s law of odd numbers: The distances traversed, during equal intervals of time, by a body falling from rest, stand to one another in the ratio:
 

You can measure your reaction time by a simple experiment. Take a ruler and ask your friend to drop it vertically through the gap between your thumb and forefinger (figure shown below). After you catch it if the distance d travelled by the ruler is \(21.0\) cm, your reaction time is:

When brakes are applied to a moving vehicle, the distance it travels before stopping is called stopping distance. It is an important factor for road safety and depends on the initial velocity \({v_0}\) and the braking capacity, or deceleration, \(-a\) that is caused by the braking. Expression for stopping distance of a vehicle in terms of \({v_0}\) and \(a\) is:

A ball is thrown vertically upwards with a velocity of \(20\) m/s from the top of a multistorey building. The height of the point from where the ball is thrown is \(25.0\) m from the ground. How long will it be before the ball hits the ground?
(Take \(g=10\) ms^–2.)
1. \(3\) s
2. \(2\) s
3. \(5\) s
4. \(20\) s