Question

Luis rushes 40m toward his truck. He notices he forgot his shoes and returns back to his house. His total travel time is 60s.

Answer 1

Answer:

1. The average speed of Luis over the 60 s is 1.33 m/s

2. The average velocity of Luis over the 60 s is zero.  

Explanation:

1. The average speed can be calculated with the following equation:

$S = \frac{d}{t}$

Where:

d: is the total distance traveled

t: is the total time = 60 s

The total distance can be calculated by the sum of the distance traveled to the truck (40 m) and the distance traveled to his home (the same 40 m), as follows:

$d = 40 m + 40 m = 80 m$

So, the average speed is:

$S = \frac{d}{t} = \frac{80 m}{60 s} = 1.33 m/s$

Hence, Luis's average speed over the 60 s is 1.33 m/s.

 

2. Now, the average velocity is a vector given by:

$v = \frac{\Delta x}{\Delta t} = \frac{x_{f} - x_{i}}{t}$

Where:

$x_{f}$: is the final distance traveled (the way to his home) = 40 m

$x_{i}$: is the initial distance traveled (the way to his truck) = 40 m

Δt: is the total time = t = 60 s

Given that Luis in his journey, returns to the same starting point (his house), the total displacement is zero, and so the average velocity is also zero:                              

$v = \frac{x_{f} - x_{i}}{t} = \frac{40 m - 40 m}{60 s} = 0$

Therefore, Luis's average velocity over the 60 s is zero.  

I hope it helps you!