Question

When C passes A, where is B?

Answer 1

You can start by defining distance, the importance of graphs. Then describe the distance-time graph and mention their significance. Then look at the graph and figure out the point where C passes A and note down the time. Then note the position of B at this time to reach the solution.

Complete step by step answer:
Distance is the length of the path travelled by a body. The distance covered is covered in meters.
Equations are useful for explaining idealized scenarios, but they don't always cut it. In many instances it is much more efficient to use an image to describe the situation. Graphs can be considered as a mathematical picture and describe real world events in a compact form. Graphs of motion are available for several types of situations based on which of the kinematic quantities (time, position, velocity, acceleration) are assigned to the X axis and the Y axis.
A distance-time graph is made to display how much distance an object covers in a given time. This slope of this graph depicts velocity. Here, in this image we see that the slopes of A, B and C are straight lines, which means that the velocities of the bodies are constant. If the velocity were non-uniform throughout the motion, the graph of the motion of the bodies would have slopes in the form of curves which represents changing velocity of the body.

In the diagram provided to us in the problem we can see that C passes A at time $= 0.6hr$ . If we look at the graph we see that on time $= 0.6hr$ , $x = 6km$ .
Hence, B is at $x = 6km$ when C passes A.

Note:
The average speed for a body over a certain time period can be calculated by dividing the distance covered with the time taken to cover this distance, i.e. ${v_{average}} = \dfrac{{\Delta x}}{{\Delta t}}$. You can also calculate the instantaneous velocity of the body by differentiating the displacement with respect to time, i.e. ${v_{}} = \dfrac{{dx}}{{dt}}$.