Two children seat themselves on a seesaw.The one on the left has a weight of 300 N while the one on the right weighs 200 N.The fulcrum is at the midpoint of the seesaw.If the child on the right is not at the end but is 1.50 m from the fulcrum and the seesaw is balanced,what is the torque provided by the weight of the child on the left? (Take ccw as positive. )
A)-300 N·m
B)300 N·m
C)450 N·m
D)-450 N·m
E)150 N·m

Question

Two children seat themselves on a seesaw.The one on the left has a weight of 300 N while the one on the right weighs 200 N.The fulcrum is at the midpoint of the seesaw.If the child on the right is not at the end but is 1.50 m from the fulcrum and the seesaw is balanced,what is the torque provided by the weight of the child on the left? (Take ccw as positive. )
A)-300 N·m
B)300 N·m
C)450 N·m
D)-450 N·m
E)​150 N·m

Quizplus · Accepted Answer

Torque is given by the formula T = Fd, where F is the force and d is the distance from the fulcrum. Since the seesaw is balanced, the torque provided by the child on the right (200 N) is equal and opposite to the torque provided by the child on the left. Let's call the distance from the fulcrum to the child on the left x. Then, we can set up the equation:

300 N(x) = 200 N(1.5 m)

Solving for x, we get:
x = 1 m

Therefore, the torque provided by the child on the left is:
T = 300 N(1 m) = 300 N·m

The direction of the torque is counterclockwise (ccw), which is positive according to the given convention.

Two Children Seat Themselves on a Seesaw