Position vs time graph

Q.

What is the total distance travelled till 30 seconds?

1. -10 m

2. 40 m

3. 10 m

4. 30 m

Q.

A stone is dropped into a river from a bridge 125 m above the water. Another stone is thrown vertically down 1.00 s after the front is dropped. The stones strike the water at the same time.

Which of these is the correct position-time curve of the stones w.r.t. the person who is throwing them?

1. 

2. 

3. 

4. 

Q. The position $\left(x\right)$ - time $\left(t\right)$ graphs for two children $A$ and $B$ returning from their school $O$ to their homes $P$ and $Q$ respectively along straight line path (taken as x-axis) are shown in figure below. Choose the incorrect statement:

1. $A$ lives closer to the school than $B$.
2. $A$ starts from the school earlier than $B$.
3. $A$ and $B$ have equal average velocities from $0$ to $t_0$.
4. $B$ overtakes $A$ on the way.

Q. The position-time graph of a particle moving along x -axis is given as

The particle reverses its direction at

1. O
2. A
3. B