Question

A scooterist travels a certain distance with speed of 50kmh and returns back at the starting point with a speed of 40kmh . calculate 1.average speed, 2. average velocity of the whole journey.

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Answer 1

Answer:

The answer will be:

1. Average speed = 400 / 9 km per hrs or 44.44 km/hrs.

2. Average velocity = 0.

Explanation:

We have given;

             Speed of scooterist while travelling some distance = 50 kmh;

           Speed of scooterist while returning from same distance = 40 kmh;

For average speed, we know that, the expression is given as;

                = Total distance / time time;                      (i)

Now, let the distance be x kilometer(s) for he is travelling same distance twice .

Hence, time taken in traveling = (x / 50) hour                    (ii)

similarly, while returning, time taken = (x / 40) hour;              (iii)

From equation (i), (ii), and (iii), it can be concluded that;

           Avg. speed = (distance travelled by scooterist in travelling + distance travelled by scooterist in returning) / (time taken in travelling the distance once + time taken in returning)

       Avg. speed = (x + x) / ($\frac{x}{50}$ + $\frac{x}{40}$);

                           = 2x / ($\frac{9x}{200}$);

                           = (200*2x) / 9x;

                           = 400x / 9x

                           = 400 / 9 km/hrs or 44.44 km/hrs

For average velocity, we know that, the expression is given as;

                = Total displacement / time time;                      (iv)

Here, the scooterist goes to some distance and then he/she arrives to his/her initial position and this deduces that she/he hasn't travelled any distance if we count for any displacement.

Hence, displacement = 0 km                  (v)  

Now, lets take time taken by scooterist, while going, be y and, while returning, be z.                                                          (vi)

From equation (iv), (v) and (vi), it can be concluded that;

           Avg. velocity= (net displacement in this whole journey) / (total time taken)

       Avg. velocity = (0) / (y+z);

                           = 0;                

That's all.

Answer 2

Answer:

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