Describe the graphical method to calculate the instantaneous speed at

1.	Describe the graphical method to calculate the instantaneous speed at a given point.
Answer» Solution :1) Consider a car moving along a straight road with varying speed. 2) Take time elapsed on X - axis and distance covered on Y - axis and PLOT a GRAPH for its motion at regular intervals of time. 3) A general case of motion with varying speed is shown in the figure. 4) The AVERAGE speed during the time interval from `t_(1)` to `t_(2)` which INCLUDES the instant `t_(3)` is `(s_(2)-s_(1))/(t_(2)-t_(1))` 5) Then we calculate average speed for a very short time interval encompassing the time at an instant `t_(3)` which is so short interval, that value of average speed would not change materially if it was made even shorter. 6) The instantaneous speed is represented by the slope of the curve at a given instant of time. 7) The slope can be found by drawing a tangent to the curve at that point. 8) The slope of the curve GIVES speed of the car at that instant.

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