Question

6
علما
A body moves psom A to B at a speed of
10 m/s and back to A along the same path at
a speed of 20 m/s
average speed and average velocity
for the journey​

Answer 1

Answer:

Average speed is the distance traveled divided by the time taken to travel …

Each leg of the journey is the same distance, call it d = |AB| (that is just maths-speak for “d is the distance from A to B”).

We are not told directly what it is… the trick with this sort of question is to just use variables for the things you don’t know and hope it all comes out OK at the end. So keep on going and just put d everywhere we’d normally want to have the actual distance.

The total distance traveled is 2d because the body does goes over the same ground twice.

The time on the first leg of the journey is d/10, and for the second part is d/20 (in seconds).

So the total time is d/10 + d/20 = 30d/200

So the average speed is distance over time:

v¯=2d30d/200=(40/3)m⋅s−1  

The second part is a trick question, sort of.

The average velocity is the total displacement divided by the total time.

Displacement is a vector … it’s the change in position.

Since the body returns to the same position it started out in, it does not change position overall, so it’s total displacement is zero. Therefore the average velocity is zero.