1. Carbon nanotubes are one of the stiffest and strongest materials known to scientists and engineers. Carbon nanotubes have an elastic modulus of 1100 GPa. If a carbon nanotube has a diameter of 15nm, determine the engineering stress sustained by the nanotube when subjected to a tensile load of 5 μN along the length of the tube. Assume that the entire cross-sectional area of the nanotube is load bearing.

2. Assume that the carbon nanotube is only deformed elastically (not plastically) under the load of 3.8 μN. The carbon nanotube has a length of 10 μm. What is the tensile elongation (displacement) of the carbon nanotube in nanometers?

3. Can you guess how these experiments were performed? Explain in details.

4. For another nanotube sample, the modulus is unknown. In addition to the tensile test, is there any other way you can determine the modulus. Explain the experimental set-up you are going to use. Provide hypothetical steps you will follow to obtain the results.