What is the average strain in a steel spike when struck by a 30kg sledge hammer?

In summary, stress and strain are physical quantities that describe the deformation of a material due to an applied force. They are caused by external forces acting on a material and can lead to changes in physical properties or even failure. There are three main types of stress: tensile, compressive, and shear, and strain can be either elastic or plastic. Both stress and strain can be measured using specialized devices or calculated using mathematical equations.
  • #1
lordbolton
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A 30kg sledge hammer strikes a steel spike of 2.30 cm diameter while moving at 20.9 cm/s. The hammer rebounds with a speed of 10.0 cm/s after 0.110 s. What is the average strain in the spike during impact?



2. F = (mvf-mvi)/t
S = (F/A)/(deltaL/initialL)
Young's modulus for steel = 2 x 10^11




3. I used (vf-vi)/t to find the force but apparently I'm supposed to use change in momentum/time. I don't understand why.
 
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  • #2
nevermind, i got it.
 

1. What is stress and strain?

Stress and strain are physical quantities that describe the deformation of a material due to an applied force. Stress is the force per unit area, while strain is the change in length or shape of a material in response to that force.

2. What causes stress and strain?

Stress and strain are caused by external forces acting on a material. These forces can be applied through tension, compression, shear, or torsion.

3. How do stress and strain affect materials?

Stress and strain can cause changes in the physical properties of a material, such as its shape, size, and strength. In some cases, they can lead to permanent deformation or even failure of the material.

4. What are the different types of stress and strain?

There are three main types of stress: tensile, compressive, and shear. Tensile stress occurs when a material is pulled apart, compressive stress occurs when a material is pushed together, and shear stress occurs when a material is twisted. Strain can be either elastic, where the material returns to its original shape after the force is removed, or plastic, where the material undergoes permanent deformation.

5. How can we measure stress and strain?

Stress can be measured using a device called a stress meter, which calculates the force per unit area. Strain can be measured using a strain gauge, which measures the change in length or shape of a material. Both stress and strain can also be calculated using mathematical equations and formulas.

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