Answer
In both the balancing acts in fig. 8.33 the center of mass of the objects lies on axis of rotation so that the torque becomes zero.
Left fig. :
The center of gravity of the spoon and the fork and the toothpick lies at the point of contact of the toothpick and the glass. So, the force exerted by the glass on the toothpick and the force due to weight of the spoon, the fork and the toothpick system will have zero net torque as these forces will pass through axis of rotation.
Right fig. :
The Center of gravity of the birds will be at its back so that the torque due to its weight is zero as the distance between the force due to weight of bird and the axis of rotation is zero in each case.
Work Step by Step
In both the balancing acts in fig. 8.33 the center of mass of the objects lies on axis of rotation so that the torque becomes zero.
Left fig. :
The center of gravity of the spoon and the fork and the toothpick lies at the point of contact of the toothpick and the glass. So, the force exerted by the glass on the toothpick and the force due to weight of the spoon, the fork and the toothpick system will have zero net torque as these forces will pass through axis of rotation.
Right fig. :
The Center of gravity of the birds will be at its back so that the torque due to its weight is zero as the distance between the force due to weight of bird and the axis of rotation is zero in each case.
