Essay: What caused World Trade Center to Collapse
National Institute of Standards and Technology (NIST) conducted a three-year thorough investigation to ascertain what really caused the twin towers to collapse. Experts were drawn from all the sectors including the private sector and they interviewed hundreds of people as well as examining video footages of the scene.
The impact caused a severe damage on the light steel, which make the external columns of the impacted floors. This is because the planes are enormous and travel at relatively higher speeds than 707s. The large mass and high speed result to a high momentum, which results in higher damages in case of an impact. This is evidenced by the location of the debris that was thrown from WTC after the impact. This leads to the observation that the impact caused lots of structural damage to the building.