Question

The forces acting on a child sitting in a seat are described by the free-body diagram shown.

Fn=100N up and down Fg=-100N

What is the net force acting on the child?

A.–100 N
B.0 N
C.100 N
D.200 N

Answer 1

B, there is no net force because the object is not moving

Answer 2

B.0 N

Step-by-step explanation:

Based on the description of the free-body diagram, there are only two forces acting on the child sitting on the seat:

- The force of gravity, Fg=-100 N, in the downward direction

- The normal reaction of the chair on the child, Fn=100 N, in the upward direction

The two forces have same magnitude but in opposite directions, so the net force (resultant of the two forces) is zero:

`F_(net)=F_n+F_g=100 N-100 N=0 N`