hi guys. david here. challenge to self: transcribe physics worksheet into blog entry. :))

Formulae:

Stress = Force / Area
Units for Stress: Pa (pascal) or N/m^2

Strain = Change in Length / Original Length
Units for Strain: none

Area of a Cylinder or Rod = Pi x Diameter^2 divided by 4

Elastic Limit = maximum stress a body can take without deformation
Refer to "Stress = F/A"

Modulus of Elasticity = Stress / Strain
Units for Modulus: Pa

Young's Modulus = longitudinal stress / longitudinal strain
Use this for objects like rods and bars which are much longer than they are wide
Y = (F / A) / (change in L / L) or (FL)/(A x change in L)
Units: Pa

Shear Modulus = ratio of shearing stress (F/A) to shearing strain (theta, also distance/length), in other words, (F/A) divided by (d/l)




WORKSHEET QUESTIONS:

1.) A woman wearing high-heeled shoes is invited into a home in which the kitchen has vinyl floor covering. Why should the homeowner be worried?

Hint: Stress is calculated by (Force divided by Area)

2.) If the elastic limit of steel is 2.48 x 10^8 Pa, determine the minimum diameter a steel wire can have if it is to support a 70kg circus performer without its elastic limit being reached.

Hint: use Stress = F/A, then calculate for D using the formula above (area of steel rod)

3.) For safety in climbing, a mountaineer uses a nylon rope that is 50m long and 1.0cm in diameter. When supporting a 90 kg climber, the rope elongates 1.6 m. Find its Young's Modulus.

Hint: Solve for area using given diameter, then apply Y = (FL)/(A x change in L). Your answer is going to be a big number.

4.) The distortion of the Earth's crustal plates is an example of shear on a larger scale. (HAHAHA. Aliw naman ako.) A particular crustal rock has a shear modulus of 1.5 x 10^10 Pa. What shear stress is involved when a 10-km layer of this rock is sheared through a distance of 5.0 m?

Hint: Use Shearing modulus = Stress / (d/l)





Good luck, people :> Sana naintindihan niyo yung mga formula sa taas.