Question

The graph shows the position as a function of time for two trains $A$ and $B$ running on parallel tracks. For time greater than $t=0$, which of the following statement is true?
($t_B$ is the time when both A and B intersect)

• A. At time $t_B$, both trains have the same velocity
• B. Both trains speed up all the time
• C. Both trains may have the same velocity at some time earlier than $t_B$
• D. Graph indicates that both trains have the same acceleration at a given time

Answer 1

The correct option is C Both trains may have the same velocity at some time earlier than $t_B$

We can see that the slope of curve $A$ is always constant, while curve $B$ does not have a constant slope, therefore, it is possible according to the graph, that the slope at some point in curve $B$ would be equal to slope of $A$. Also this would be only be possible before $t_b$ due to the shape of the curve. Therefore, option (c) is correct.