Chapter-2 Q031 - Physics For Engineers And Scientists - Solutions
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Question 31 - Problems - Chapter 2¶

Problem:¶

A horse trots around a quarter-mile track three complete times in 1 min 40 s.

Question:¶

a) What is the average speed?

b) What is the average velocity?

Solution:¶

The horse runs around a track so his displacement $\Delta s = 0m$

The traveled way against it is $s = 3x0.25mile = 0.75$ mile

The time to complete his race is $t = 1m40s$

In [1]:
import numpy as np
import pint
u = pint.UnitRegistry()
d_s = 0 * u.m
s = 3 * 0.25 * u.mile
t = 1*u.min + 40 * u.s
v_v = d_s / t
v_s = s/t
print(f'a) The average speed is: {v_s.to(u.m / u.s):.1f}')
print(f'b) The average velocity is: {v_v.to(u.m / u.s):.1f}')

a) The average speed is: 12.1 meter / second
b) The average velocity is: 0.0 meter / second


 سُوۡرَةُ حٰمٓ السجدة / فُصّلَت ثُمَّ اسْتَوَىٰ إِلَى السَّمَاءِ وَهِيَ دُخَانٌ فَقَالَ لَهَا وَلِلْأَرْضِ ائْتِيَا طَوْعًا أَوْ كَرْهًا قَالَتَا أَتَيْنَا طَائِعِينَ ﴿١١ فَقَضَاهُنَّ سَبْعَ سَمَاوَاتٍ فِي يَوْمَيْنِ وَأَوْحَىٰ فِي كُلِّ سَمَاءٍ أَمْرَهَا ۚ وَزَيَّنَّا السَّمَاءَ الدُّنْيَا بِمَصَابِيحَ وَحِفْظًا ۚ ذَٰلِكَ تَقْدِيرُ الْعَزِيزِ الْعَلِيمِ ﴿١٢ Surah Fussilat: Thereafter turned He to the heaven and it was as smoke, and said Unto it and Unto the earth: come ye twain, willingly or loth. They said: we come willingly. (11) Then He decreed them as seven heavens in two days, and revealed Unto each heaven the command thereof; and We bedecked the nether heaven with lamps and placed therein a guard. That is the ordinance of the Mighty, the Knower. (12) De hemelen en aarde (waren) een samenhangende massa. Wij hebben ze toen van elkaar gescheiden… Wij hebben de hemel tot een beschermend dak gemaakt … en de dag en de nacht, de zon en de maan geschapen. (Koran 41 11:12) Copyright (c) 2000-2020 - Jean Paul Mertens - ON7AMI - formal ON1AMI - Grote Steenweg 86 - 9840 Zevergem - Belgium - Europe