Question
Tue September 11, 2012 By: Priyal

why is it easier to open a pen with two fingers rather than one?

Expert Reply
Wed September 12, 2012
Couple is a pair of equal parallel forces that are opposite in direction not acting along same line of action. A couple is always needed to produce rotation. The turning effect, or moment, of a couple is measured by the product of the magnitude of either force and the perpendicular distance between the action lines of the forces.
 
To open a pen ,we use two fingers and we apply equal forces at the ends of both fingers in opposite directions.
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