Question

The pole in the figure below is at a 90° bend in a power line and is therefore subjected to more shear force than ones in straight parts of the line. The tension in each line is 4.60 x 10" N, at the angles shown The pole is 15.0 m tall, has a 16.0 cm diameter and can be considered to have 5.0 X10 N/m? the strength of hardwood. Assume Young's modulus to be 7.5 X10 N/m and the shear modulus is (a) Calculate the compression (in mm) of the pole * Consider the component of the tension from the two wires that (b) Find how much it bends in mm) and in what direction. magnitude (e) Find the tension in ) in a guy were used to keep the pole straight if it is attached to the top of the pole at an angle of 30.0" with the vertical (Clearly, they wire must be in the opposite direction of the bend.)

Answer 1

PageNoD AnSwe T 0 'gu 80 300 Accosn&img to ven data, Th pole is at 9o' bend in a Power lime. The tension in each line i u60 x 10N The Pole is 15.0 m łall, hasa 16-0 Cm diameten oung .5x io4 n/m* modulu Shaar module Due to applied touce tha change AL = YA The Elatic Modulus Y

Pogewo Fonca Pen unit Aua - A mitial dength The foac otension pooiallel to tha lamgth ot pol i^ F- TCOS80 of h pole i The Cooss section aoua 2 A TT &= diameten of thu Pols a Caluclate the CompmuSsion of the pole. AL - Substitute 1.5 KtoNm2 fo Y 6.0 cm fo d CoS8o G0 C Icm

geнов C5.0m) (a)(u60 xt0*) Cosgo 60xt0N) coS8 T 958 53.uof 60318 5t 8^5 5891255 35 x 10 1 5 mm Compoulin pola =5mm bThe bendimg of Pole is fooca Pependiculan to th Poia Shewing modutus the Po im diouctim to 2T(CoS 80)eana

Pegevо The bending Poli id (aT (cosso)osus) Ax TTd Substitute 5.0xioN/m for S, 15 0 m (u60x10Cos0)Ccosu(5 0m) Ax - 8 (4.60 X10N) (o36481477)01061812(1) (5.0x t0 )T16 K 10) 36 8000 (0-17 26481a10110181)(15) 40 31 38 S9. 678 618 68552216uxlo =6 mm Th Polu will bend by

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