Opening Jars

When I was visiting my aunt in Minnesota, my younger counsins wanted nutella sandwiches for breakfast. To open the jar of nutella, my aunt used a jar opener much like the one featured here (I didn't have my camera at the time). I instantly connected this with the concept of torque. In order to open the jar, she needed to exert a torque, or force causing rotation, on the lid. Her torque was insufficient to open the lid without the help of the jar opener. How did the jar opener open the lid if the amount of force my aunt exerted was the same? It increased the lever arm, or distance from the axis. Increasing the distance is the only other way to increase torque other than increasing force.