Question
Tue September 11, 2012 By: Priyal

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

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.
Related Questions
Mon July 17, 2017

# This is the answer of question 15 in selina physics class 10 solutions which you have given. What is the reason of force being applied in this direction only? To lift up the wheel on the platform, Point X will become the point of rotation of the wheel. Why can't the force be applied at the diameter of the wheel so that the perpendicular distance of the line of action of force from the axis of rotation is maximum? This is one of the factors affecting torque. Torque is directly proportional to the perpendicular distance of the line of action of force from the axis of rotation. Therefore, by applying the force at the diameter, the perpendicular distance increases and due to this, the moment of force also increases. therefore, by applying minimum effort, the wheel can be raised.

Tue July 11, 2017

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