Question

Which of the following speed-time graphs exists in nature?

Answer 1

We are given the speed – time graph of three bodies and we are asked to find which of them exists in nature. To find which one is correct, we need to check each of the graphs and see which of them obeys the conditions of velocity and velocity time relation. Thus we get the solution.

Complete step by step answer:
In the question we are given three speed – time graphs.
We need to find which of the given graphs exists in nature.
Let us consider the figure A.
In this graph, we can see that the speed of the body becomes negative at certain times. We know that the speed of any object can be zero but never be negative. Hence this graph does not exist in nature.
Now let us consider figure B. in this graph we can see that velocity is plotted in y – direction and time is plotted in x – direction. The speed of the body is always positive and the body has only one value of speed at one time. Therefore this speed – time graph exists in nature.
Now let us see the figure C. In this figure also velocity is plotted in y – direction and time is plotted in x – direction. But in this case the speed of the body is said to have negative value at certain times. Since velocity of a body does not possess negative value, we can say that this graph also does not exist in nature.
Therefore we can see that only graph B is correct.

So, the correct answer is “Option B”.

Note:
A speed – time graph shows the motion of a body accelerating with a velocity at a time ‘t’.
In case of a speed – time graph, speed of the body is always plotted on the y – axis and time is plotted on the x – axis. The slope or gradient of the graph gives acceleration of that body and area under the graph gives the total distance traveled by the body.