1. General Physics for Medical Sciences
Homework 3
Instructor: Dr. Hassan Ashour
Due Date: Nov 18, 2009
Solve the following questions
1. Assume that Young’s modulus for bone is 1.5 × 10 N/m and that a bone will fracture if
more than 1.50 × 10 N/m is exerted. (a) What is the maximum force that can be
exerted on the femur bone in the leg if it has a minimum effective diameter of 2.50 cm?
(b) If a force of this magnitude is applied compressively, by how much does the 25.0-cm-
long bone shorten?
2. (a) Find the minimum diameter of a steel wire 18 m long that elongates no more than 9
mm when a load of 380 kg is hung on its lower end. (b) If the elastic limit for this steel
is 3 × 10 N/m , does permanent deformation occur with this load?
3. Calculate the density of sea water at a depth of 1000 m, where the water pressure is
about 1.0 × 10 N/m . (The density of sea water is 1.03 × 10 kg/m at the surface.)
4. When water freezes, it expands by about 9%. What would be the pressure increase
inside your automobile’s engine block if the water in it froze? (The bulk modulus of ice
is 2 × 10 N/m .)
JGood Luck J
Hassan Ashour
