Science: average speed/velocity?

Question

A stationary ball accelerates until, after 2 seconds it is moving at 10m/s.

At this point it's acceleration is 5m/s^2, it has travelled 10m and it's average speed is 5m/s.

The ball then continues to move at 10m/s for a further 5 seconds, in this time it travels 50m. It has now travelled a total of 60m. What is its average speed for the whole distance?

I thought you could find it using the formula:

Average Speed = (V + U)/ 2

= (10 + 0)/2

=5m/s

however this is the same average speed as when the ball had only travelled the first part of the journey, which i don't think is correct.

What am i doing wrong?

Answer 1

I couldn't understand your question completely but I'll give you one example that may help out...

a car travels certain distance say 48m at 6 Km/hr while going and 8 km/hr while returning..?

so according to you.. average speed =( 6 + 8)/2 = 7 km/hr

but time taken for ----> going = 48 / 6 = 8

                          ----> coming back = 48 / 8 = 6

so total time taken = 8 + 6 = 14

so total distance = 48 + 48 = 96

so average velocity = 96 / 14 = 6.85

Answer 2

(average speed) = (distance traveled) / (time)

(avg speed) = ( 60m ) / (7s)

(avg speed) = 8.57 m/s

Answer 3

Speed is not the same as velocity. Ask your teacher.

Answer 4

I have carefully read your question, in view of some of the other answers. I can only interpret your question that the ball moves in one direction in a straight line. Under these circunstances diplacement is the same as distance, so speed will be numerically  the same as velocity.

What is the distance covered? 60m

How long did it take to cover this distance? 7seconds

Average speed, distance / time

Average speed = 60/7

Average speed = 8.57m/s

For the pedants:

Displacement = 60m

Time taken = 7 seconds

Average  Velocity = displacement /time

Average velocity = 60/7

Average Velocity = 8.57m/s in the original direction.

You will notice that to be scientifically correct, when answering for velocity it is necessary to state a direction. This does not apply to speed.