How is instantaneous speed different from average speed?

Answer 1

I drive from A to B 120 klicks. it takes me two hours because I stop for coffee and read a newspaper. While I am driving my speed might be 80kph some of the time, that is, at any one instant. While I am sitting in the cafe, my instantaneous speed is zero. Average speed, 60kph.

Answer 2

Your instantaneous speed is your speed at any given moment. Your average speed is your speed measure for a whole trip. You can calculate average speed by dividing the total distance traveled by the time taken to travel that distance.

If you drive down a road with a lot of traffic lights your instantaneous speed might be zero if you are stopped at a red, or 55 mph if the light is green. Unless you hit every light green the average speed will be somewhere between the two.

Answer 3

Average speed is like taking a motion picture of a car trip through the windshield, including the odometer (distance) and clock in the foreground and then calculating the the total distance traveled divided by the total time. Instantaneous speed is determined by taking a snapshot during the trip and observing the speedometer and clock time at any desired time (or looking at any single frame of the motion picture).

Answer 4

The instantaneous speed of a body is its speed at that particular instant of time.
dV=dX/dT, where dX and dT are very small intervals of distance and time to measure the instantaneous speed.

Average speed is the average of the speeds of the body covering the distance over a given period(not instant but longer) of time
If the body begins with an initial velocity u and has a final velocity v, the avg. velocity is (u+v)/2