A vertical solid steel post of diameter d = 21cmand length L = 2.40m is required

Question

A vertical solid steel post of diameter d = 21cmand length L = 2.40m is required to support a load of mass m = 8000kg . You can ignore the weight of the post. Take free fall acceleration to be g=9.8m/s2.

Part A

What is the stress in the post?

Express your answer using two significant figures.

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Part B

What is the strain in the post?

Express your answer using two significant figures.

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Part C

What is the change in the post's length when the load is applied?

Express your answer using two significant figures.

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A vertical solid steel post of diameter d = 21cmand length L = 2.40m is required to support a load of mass m = 8000kg . You can ignore the weight of the post. Take free fall acceleration to be g=9.8m/s2.

Part A

What is the stress in the post?

Express your answer using two significant figures.

P =   Pa  

SubmitMy AnswersGive Up

Part B

What is the strain in the post?

Express your answer using two significant figures.

?LL =

SubmitMy AnswersGive Up

Part C

What is the change in the post's length when the load is applied?

Express your answer using two significant figures.

?L =   m  

Submit

Explanation / Answer

A)

stress is the Ratio of exernal force to the cross sectional area

here by using the formula

stress = Force / Area

stress = m * g / pie * r^2

P = 8000 * 9.8 / 3.14 * 0.105^2

P = 78400 / 0.0346

P = 2.26 * 10^6 pascals

stress in the post is 2.26 *10^6 pa

B)

strain = stress / young's modulus

young's modulus for the steel is 200 * 10^9

then

strain = 2.26 * 10^6 / 200 * 10^9

strain = 0.0113 * 10^-3

strain = 1.13 * 10^-5

the strain in the post is 1.13 * 10^-5

C)

increase of length = orignal length * strain

increase of length = 2.40 * 1.13 * 10^-5

increase of length = 2.71 *10^-5 m

so the change in the length of the steel post is 2.71*10^-5 m

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