II. Workout the following problems 8. A vertical, solid steel post 25 cm in diameter and 2.50 m long is required to support a load of 8000 kg . You can ignore the weight of the post. What are (a) the stress in the post; (b) the strain in the post; a (c) the change in the post's length when the load is applied?

प्रश्न 20. एक कण सरल आवर्त गति से एक सरल रेखा पर गतिमान है। जब कण की केन्द्र से दूरी \( x_{1} \) तथा \( x_{2} \) है तथा इसक वेग कमशः \( \nu_{1} \) तथा \( v_{2} \) है। सिद्ध कीजिये कि आवर्त काल होगा

\( \frac{\text { Exercice } 15}{\text { Deux charges électriques } q_{A}=1 \mathrm{mC} \text { et } \mathrm{q}_{\mathrm{B}}=-3 \mathrm{mC} \text { sont }} \) placées en A et B distants de 20 cm . 1) Détermine les caractéristiques du vecteur champ électrique au point M , milieu de AB (faire un schéma précis). 2) On remplace les deux charges \( \mathrm{q}_{\mathrm{A}} \) et \( \mathrm{q}_{\mathrm{B}} \) respectivement par \( \mathrm{q}_{1}=-2 \mu \mathrm{C} \) et \( \mathrm{q}_{2}=-5 \mu \mathrm{C} \). a) Détermine la valeur du champ électrique au point M . b) Quel doit être la position du point M pour avoir \( \mathrm{E}_{\mathrm{M}}=0 \) ?

Two forces act at a point the magnitude of the two forces 6,8 newton and the meas f the included angle between them \( \theta \in\left[0, \frac{\pi}{2}[\right. \), then the magnitude of their resul ould be equal \( \qquad \) newton. 5 (b) 10 (c) 12 (d) 16

Exercise 2: 1. Obtain the moment of inertia tensor of a thin uniform ring of radius R , and mass M, with the origin of the coordinate system placed at the center of the ring, and the ring lying in the xy plane. 2. Obtain the moment of inertia tensor of a uniform hollow sphere of radius R , and mass M , with the origin of the coordinate system placed at the center of the sphere. Note that this problem can be done by dividing the sphere into a large number of infinitesimally thin rings.

2. Aball is thrown upward with a speed of \( 19.6 \mathrm{~m} / \mathrm{s} \). a. How high doesit go until its upward speed decreases to zero. b. How long does the ball take in this upward trip? \( c \). How long does the ball take to return to the initial position? \( d \). What will be its velocity then