Answer:
The person needs to apply 25 N to balance the seesaw
Step-by-step explanation:
Moment
The moment of a force is a measure of its tendency to cause a body to rotate about a specific point or axis.
The moment M of a force F located at a distance x from the axis of rotation is calculated as follows:
M = F.x
The image shows a moment of M=100 N.m is needed to be applied to balance the seesaw. It can also be noted that the distance to the pivot is x=4 m
To calculate the force needed to balance the seesaw, we solve for F:


F = 25 N
The person needs to apply 25 N to balance the seesaw