Question

a person walks first ata speed of 5m/s along a straight line from point a to b and then back along from b to a at a constant speed of 3m/s. what is the average speed of the whole journey? what is the verage velocity of the entire journey

Answer 1

$\huge{\star}{\boxed{\boxed{\red{\sf{Answer :}}}}}{\star}$

Speed from A to B (S1) = 5 m/s

Speed from B to A(S2) = 3 m/s

======================================

Average speed

We have formula :-

$\LARGE{\boxed{\boxed{\sf{Speed_{avg} \: =\: \frac{2(S1 \: \times \: S2)}{S1 \: + \: S2}}}}}$

Average speed = 2[5 * 3]/8

Average Speed = 2(15)/8

Average speed = 30/8

$\large{\boxed{\boxed{\green{\sf{Speed_{avg} \: =\: 3.75 \: m/s}}}}}$

===========================================

As the person reaches again to its starting point ,

Displacement = 0

If displacement is zero then ,

$\LARGE{\boxed{\boxed{\sf{Velocity \: = \: \frac{Displacement}{Time}}}}}$

Then velocity will be zero.

$\large{\boxed{\boxed{\green{\sf{Velocity_{avg} \: = \: 0 \: m/s}}}}}$