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A closely coiled helical spring of 20 cm mean diameter is having 25 coils of 2 cm diameter rod. The modulus of rigidity of the material if 107 N/cm2. What is the stiffness for the spring in N/cm? 
  • a)
    50
  • b)
    100
  • c)
    250
  • d)
    500
Correct answer is option 'B'. Can you explain this answer?
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A closely coiled helical spring of 20 cm mean diameter is having 25 co...
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A closely coiled helical spring of 20 cm mean diameter is having 25 co...
Given data:
Mean diameter of the spring (D) = 20 cm
Number of coils (N) = 25
Diameter of the rod (d) = 2 cm
Modulus of rigidity (G) = 107 N/cm²

We need to find the stiffness of the spring.

Stiffness of a spring is given by the formula:
Stiffness (k) = (G * d⁴ * N) / (64 * D³)

Let's calculate the stiffness step by step.

1. Calculate the radius of the mean coil diameter:
Radius (R) = D / 2 = 20 cm / 2 = 10 cm = 0.1 m

2. Calculate the radius of the rod:
Radius of rod (r) = d / 2 = 2 cm / 2 = 1 cm = 0.01 m

3. Calculate the mean coil circumference:
Mean coil circumference (C) = 2πR = 2π * 0.1 m = 0.2π m

4. Calculate the shear strain energy stored in one coil of the spring:
Shear strain energy stored (U) = (π²G * r⁴ * C²) / (64R) = (π² * 107 N/cm² * (0.01 m)⁴ * (0.2π m)²) / (64 * 0.1 m)

5. Calculate the total shear strain energy stored in the spring:
Total shear strain energy stored (U_total) = U * N = U * 25

6. Calculate the stiffness of the spring:
Stiffness (k) = U_total / (0.01 m) = (U * 25) / (0.01 m)

Now let's plug in the values and calculate the stiffness.

U = (π² * 107 N/cm² * (0.01 m)⁴ * (0.2π m)²) / (64 * 0.1 m)
U_total = U * 25
k = (U * 25) / (0.01 m)

After performing the calculations, we find that the stiffness of the spring is approximately 100 N/cm. Therefore, the correct answer is option B.
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A closely coiled helical spring of 20 cm mean diameter is having 25 coils of 2 cm diameter rod. The modulus of rigidity of the material if 107 N/cm2. What is the stiffness for the spring in N/cm?a)50b)100c)250d)500Correct answer is option 'B'. Can you explain this answer?
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A closely coiled helical spring of 20 cm mean diameter is having 25 coils of 2 cm diameter rod. The modulus of rigidity of the material if 107 N/cm2. What is the stiffness for the spring in N/cm?a)50b)100c)250d)500Correct answer is option 'B'. Can you explain this answer? for Mechanical Engineering 2024 is part of Mechanical Engineering preparation. The Question and answers have been prepared according to the Mechanical Engineering exam syllabus. Information about A closely coiled helical spring of 20 cm mean diameter is having 25 coils of 2 cm diameter rod. The modulus of rigidity of the material if 107 N/cm2. What is the stiffness for the spring in N/cm?a)50b)100c)250d)500Correct answer is option 'B'. Can you explain this answer? covers all topics & solutions for Mechanical Engineering 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for A closely coiled helical spring of 20 cm mean diameter is having 25 coils of 2 cm diameter rod. The modulus of rigidity of the material if 107 N/cm2. What is the stiffness for the spring in N/cm?a)50b)100c)250d)500Correct answer is option 'B'. Can you explain this answer?.
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