Leaving the Coffee Shop

With finals coming up soon, I have been needing a lot of caffeine to get me through long nights of homework. Recently, I took a trip to Starbucks to indulge in a holiday drink. I had not been to this particular Starbucks before so I was unfamiliar with the layout. Once I had my tasty drink in my hand, I put out my other hand to push open the door but unfortunately, I pushed on the wrong side of the door (the side with the hinges). Because of this, it was very difficult for me to open the door, which resulted in my embarrassment. After I made it back to my car, I thought about the physics behind my embarrassing moment. I remembered that torque increases with distance from the axis of rotation, which was why it was so difficult for me to open the door while pushing on the side with the hinges. Doing some quick calculations, I estimated the torque I used to open the door using T=Frsinθ. Since I was pushing straight on the door, my angle was 90º so the sine component in the torque equation was equal to 1. The door was about 1 meter wide and my distance from the axis of rotation was about 1/10 m, which would be r. Thus my torque was equal to 0.1F (where F is the force I exerted). If I had pushed on the correct side of the door, my distance from the axis of rotation would have been approximately 1 m so my torque would have been equal to 1F. This means the torque when I pushed on the wrong side of the door was much less than if I had pushed on the right side of the door. This is why I was able to open the door, but it took longer than it would have if I pushed on the right side.