Mommy help, I'm stuck inside!
If you watch little kids try to open doors, they will often just push anywhere on the door, rather than on the edge like adults do. This is because they don't understand that it's easier to open a door if you push on the edge. But how much easier? Consider the following situation: you push on a door perpendicularly at a horizontal distance from the hinge with a force , thereby opening the door with some angular acceleration . Let be the amount of force you'd need to exert to open the door with the same angular acceleration, but pushing perpendicularly at a horizontal distance from the hinge. What is ?
The answer is 0.5.
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1 solution
To achieve a certain amount of angular acceleration you need to exert a certain torque. The torque is the same therefore no matter where you push. The torque is r 0 F 0 = r 1 F 1 = ( 2 r 0 ) F 1 since you push perpendicularly in both cases. Therefore F 1 / F 0 = 0 . 5 .