Chapter-2 Q002 - Physics For Engineers And Scientists - Solutions
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# Question 2 - Problems - Chapter 2¶

## Problem:¶

The world record for the 100-yard run is 9.0 s

## Question:¶

What is the average speed in miles per hour?

## Solution:¶

Distance $s = 100yards$

Time $t = 9.0s$

Average speed $v = \frac{s}{s}$ yard / s

There are 3600 seconds in 1 hour

There are 1760 yards in 1 mile

In [1]:
Distance = 100
Time = 9
Speed_ys = Distance/Time # in yards per second
Speed_yh = Speed_ys * 3600 # in yards per hour
Speed_mh = Speed_yh / 1760 # in miles per hour
# limit to 2 significant figures as time is given in 2 significants too
print(f'The speed of this world record is {Speed_mh:.0f} Miles per hour')

The speed of this world record is 23 Miles per hour


 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