Chapter-2 Q033 - Physics For Engineers And Scientists - Solutions

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Question 33 - Problems - Chapter 2

Problem:

A squirrel walks along a telephone cable, occasionally stopping, even turning back once before proceeding.

The squirrel's position as a function of time is shown in Figure below.

Squarel on a telegraph-wire

Question:

a) What is the average speed for the entire time shown, 0<t<30 s?

b) The average velocity for the entire time?

Solution:

The time of the part The displacement of the part
$$\Delta t_1 = 8s$$ $$\Delta s_1=6m$$
$$\Delta t_2 = 4s$$ $$\Delta s_2=0m$$
$$\Delta t_3 = 6s$$ $$\Delta s_3=6m$$
$$\Delta t_4 = 2s$$ $$\Delta s_4=0m$$
$$\Delta t_5 = 2s$$ $$\Delta s_5=-2m$$
$$\Delta t_6 = 2s$$ $$\Delta s_6=0m$$
$$\Delta t_7 = 6s$$ $$\Delta s_7=6m$$
In [1]:
import numpy as np
t = 8 + 4 + 6 + 2 + 2 + 2 + 6
d_s = 6 + 0 + 6 + 0 - 2 + 0 + 6
s = 6 + 0 + 6 + 0 + 2 + 0 + 6
v_v = d_s / t
v_s = s/t
print(f'a) The squarel\'s average speed is: {v_s:.2f} m/s')
print(f'b) The squarel\'average velocity is: {v_v:.2f} m/s')
a) The squarel's average speed is: 0.67 m/s
b) The squarel'average velocity is: 0.53 m/s

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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