A horizontal plane supports a plank with a bar of mass m=1kg placed on it and attached by alight elastic non deformed cord of length l_(0)=40 cm to a point O as shown in fig. The coefficient of friction between the bar and the plank equal to mu=0.2. The plank is slowly shifted to the right until thebar starts sliding over it.It occurs at the moment when the card deviates from the vertical by an angle theta=30^(@), then the work that has been performed by that moment by the friction force acting on the bar in the reference frame fixed to the plane is N/100J,then find N

A horizontal plane supports a plank with a bar of mass m=1kg placed on

1.	A horizontal plane supports a plank with a bar of mass m=1kg placed on it and attached by alight elastic non deformed cord of length l_(0)=40 cm to a point O as shown in fig. The coefficient of friction between the bar and the plank equal to mu=0.2. The plank is slowly shifted to the right until thebar starts sliding over it.It occurs at the moment when the card deviates from the vertical by an angle theta=30^(@), then the work that has been performed by that moment by the friction force acting on the bar in the reference frame fixed to the plane is N/100J,then find N
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