question one:
the maximum compressional stress that a human bone can withstand is 2.4*10^7 N/m^2 before it breaks. The pelvis, the large bone connecting the legs to the spine, has an average cross-sectional area of 3.9*10^-4 m^2. What is the maximum shear force that can be applied to the pelvis?

question two:
A long coil sring is stretched 13.2 inches with two people each pulling with a force of 20 lb in opposite directions. One end of the spring is then attached to a wall, and both people now pull on the other end (in the same direction) each with a force of 20 lb. How much does the spring now stretch?

Question one:
You're given the stress (aka force) any human bone can withstand in force/meters^2
Then they give you the specific cross sectional area of a particular human's pelvis in meters^2.
Then they ask what is the amount of force the pelvis can handle

just trying to understand what exactly is being asked should make this problem very simple and only require your common sense.

If that fails... just look at the units of measurements you are given and determine what units of measurement your answer should have then see what you can do with the 2 given numbers to get there

Let me know if the hint was enough


Question two:
Again try to reason the problem out and understand what is really being asked. Id be glad to further discuss this with you after you've given it a try.

You dont have to know the following formula assuming you have the common knowledge of what a spring even is but if it helps you here you go:

F = -k × x

Where:

F is force

k is the spring constant (e/ this varies depending on the strength of the spring, e.g. a spring made of a less malleable metal would be stronger than a spring made from a softer and more malleable metal)

x is the distance the spring stretches/compresses from resting position (in this case stretches)

This post was edited by Ramy on Feb 28 2017 12:30am