The length of an elastic string is a metre when the longitudinal tension is 4 N and b metre when the longitudinal tension is 5 N. The length of the string in metre when the longitudinal tension is 9 N is

(1) a - b                                             

(2) 5b - 4a

(3) 2b -14a                                       

(4) 4a - 3b

Subtopic:  Young's modulus |
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How much force is required to produce an increase of 0.2% in the length of a brass wire of diameter 0.6 mm ?

(Young’s modulus for brass = 0.9×1011N/m2)

(a) Nearly 17 N                        (b) Nearly 34 N

(c) Nearly 51                        (d) Nearly 68 N

Subtopic:  Young's modulus |
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A 5 m long aluminium wire Y=7×1010N/m2 of diameter 3 mm supports a 40 kg mass. In order to have the same elongation in a copper wire Y=12×1010N/m2 of the same length under the same weight, the diameter of the copper wire should be, in mm:

(a)   1.75                                   (b)   1.5

(c)   2.5                                     (d)   5.0

Subtopic:  Young's modulus |
 60%
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A steel wire of 1 m long and  cross section area 1 mm2 is hang from rigid end. When mass of 1kg is hung from it then change in length will be: (given Y=2×1011N/m2)

(1)   0.5 mm                             

(2)   0.25 mm

(3)   0.05 mm                           

(4)   5 mm

Subtopic:  Young's modulus |
 77%
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An iron rod of length 2m and cross section area of 50 X 10-6 m2 , is stretched by 0.5 mm, when a mass of 250 kg is hung from its lower end. Young's modulus of the iron rod is-

(1) 19.6×1010N/m2                         

(2) 19.6×1015N/m2

(3) 19.6×1018N/m2                         

(4) 19.6×1020N/m2

Subtopic:  Young's modulus |
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In which case, there is a maximum extension in the wire, if the same force is applied on each wire?

(1) L = 500 cm, d = 0.05 mm

(2) L = 200 cm, d = 0.02 mm

(3) L = 300 cm, d = 0.03 mm

(4) L = 400 cm, d = 0.01 mm

Subtopic:  Hooke's Law |
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The extension of a wire by the application of load is 3 mm. The extension in a wire of the same material and length but half the radius by the same load is -

(1) 12 mm                                 

(2) 0.75 mm

(3) 15 mm

(4) 6 mm

Subtopic:  Young's modulus |
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The isothermal elasticity of a gas is equal to

(1) Density                                     

(2) Volume

(3) Pressure                                    

(4) Specific heat

Subtopic:  Stress - Strain |
 65%
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The adiabatic elasticity of a gas is equal to
1. γ × density
2. γ × volume
3. γ × pressure
4. γ × specific heat

Subtopic:  Stress - Strain |
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The compressibility of water is 4×10-5 per unit atmospheric pressure. The decrease in volume of 100 cubic centimeter of water under a pressure of 100 atmosphere will be -

(a) 0.4 cc           (b) 4×10-5cc

(c) 0.025 cc       (d) 0.004 cc 

Subtopic:  Shear and bulk modulus |
 65%
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