Chapter-2 Q004 - Physics For Engineers And Scientists - Solutions


Amateur Radio and Astronomy website. JO10UX

Question 4 - Problems - Chapter 2


During the fall, the monarch butterfly migrates some 3500 km from the Nord-Eastern of the United States to Mexico.


Guess the speed of the butterfly and estimate how long it takes to make his trip


Some sientific facts on the migrating speed of the Monarch butterfly can be found if you click here

Cruise speed of the Monarch butterfly is estimated at 18 km/h, but the average speed during his migration is calculated to be 9 km/h

They fly only at daylight and in fall the mean daylight in California is 10 hours.

Distance $s = 3500 km$

Time $t = \frac{s}{v}$

Average speed $v = 9$ km/h

In [1]:
Distance = 3500 # in km
Speed_km_h = 9 # in km/h
Time_h = Distance / Speed_km_h
# limit to 2 significant figures as distance is given in 2 significants too
print(f'The time for this migration is {Time_h:.0f} hours') 
Time_d = Time_h / 10
print(f'The time for this migration in days is {Time_d:.0f} days at a mean of 10 hours a day.')
The time for this migration is 389 hours
The time for this migration in days is 39 days at a mean of 10 hours a day.

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)

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