Question

A car travels along a straight road to the east for 100 meters in 4 seconds, then go to west for 50 meters in one second. Determine the average speed and average velocity.

Answer 1

Given,

The car goes 100 metres in the east direction,in 4 seconds.

The car goes 50 metres in the west direction,in 1 second.

To find,

The average velocity and average speed of the car.

Solution,

Speed is a scalar unit which means, direction is not necessary in this case. We can simply divide the total covered distance by the total taken time,in order to calculate the average speed.

So, average speed = (100 m + 50 m)/(4sec + 1sec) = (150m/5sec) = 30m/s

Now, velocity is a vector unit,which means direction is necessary in this case. We need to find the displacement (distance between starting point and ending point of the journey) and we need to divide the displacement with total taken time.

Here,east and west are opposite directions.

So, displacement = 100 m - 50 m = 50 m in east direction

Average velocity = 50m/5sec = 10m/sec

Hence,the average speed is 30m/s and the average velocity is 10m/sec.

Answer 2

Answer:

Concept :

Both average speed and average velocity have the same SI unit and other standard units of measurement. The formulas for calculating average speed and average velocity are nearly identical, v = D/t, s = d/t, with the exception that in the first case the direction must be specified.

Given :

A automobile travels 100 metres east in four seconds and then 50 metres west in one second on a straight route. Calculate your average speed and velocity.

Find :

Find the average speed and average velocity

Answer :

Although speed is a scalar unit, it does not require direction in this case. To get the average speed, simply divide the whole distance traversed by the total time taken.

$Distance=100 m+50 m$

               $= 150 m$

$100 m- 50 m = 50 m, to. east = Displacement$

$Time .elapsed = 4 s + 1 s$

                      $=5 s$

$Average .speed = \frac{Distance}{time}$

                       $=\frac{150m}{5s}$

                       $30m/s$

∴ average speed = 30 m/s

$Average. velocity = \frac{displacement}{time}$

                           $=\frac{50m}{5s}$

                           $= 10 m/s$

∴ average velocity = 10 m/s

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