Question 32 - Problems - Chapter 2

Problem:

A dog runs 35 m to catch a Frisbee in 4.5 s, turns quickly and trots 22 m back in 3.6 s, but then stops to guard the Frisbee.

Question:

a) What is the dog's average speed?

b) What is the dog's average velocity?

Solution:

The dog does not return completely so $\Delta s = 35m - 22m = 13m$

The way the dog traveled is $s = 35 + 22 = 57$ m

The time to complete his track is $t = 4.5 + 3.6 = 8.1s$

import numpy as np
d_s = 13
s = 57
t = 8.1
v_v = d_s / t
v_s = s/t
print(f'a) The dog\'s average speed is: {v_s:.1f} m/s')
print(f'b) The dog\'average velocity is: {v_v:.1f} m/s')

a) The dog's average speed is: 7.0 m/s
b) The dog'average velocity is: 1.6 m/s