Final answer:
To find the mass of the second child on a seesaw, the principle of torque is used. Torque for both children should be equal since they are in equilibrium. The normal force at the pivot is the combined weight of both children and possibly the seesaw itself.
Step-by-step explanation:
Part A: Mass of the Second Child
To solve for the mass of the second child on a seesaw, we can apply the principle of torque. To balance the seesaw, the torques exerted by both children about the pivot must be equal. Torque (or moment) is the product of force and the distance from the pivot point; in this case, the force is due to the weight of the child (mass times acceleration due to gravity, g). The torque equation can be written as:
torquechild 1 = torquechild 2
where:
- masschild 1 x gravity x distancechild 1 = masschild 2 x gravity x distancechild 2
Given that the mass of child 1 is 33.4 kg and the distance is 2.14 m, if we solve the equation for the unknown mass of the second child, we find that:
masschild 2 = (masschild 1 x distancechild 1) / distancechild 2
Since the mass of the first child and their distance from the pivot are known, as well as the distance of the second child from the pivot (from the previous problem), we can calculate the mass of the second child.
Part B: Normal Force at the Pivot Point
The normal force at the pivot point is the sum of the weights of both children and the seesaw. Since this is an equilibrium problem where the net force is zero:
Fp = weightchild 1 + weightchild 2 + weight of the seesaw
If the seesaw's weight is not given, it is typically assumed to be negligible for simplicity; however, in reality, the weight of the seesaw would need to be included when calculating the normal force.