Need help with a seesaw torque question.

In summary, Halle and Susan, each weighing 40 kg, are sitting on a stationary seesaw that is 4.50 m long. When Susan jumps off, an unbalanced torque is created. Using the equation torque = F * r, with F = 392 N and r = 2.25 m, the unbalanced torque can be calculated. The distance from the pivot point of the seesaw to Susan is assumed to be half of the total length of the seesaw.
  • #1
paperdoll
69
0

Homework Statement


Halle and Susan, each of mass 40 kg are sitting at opposite ends of a playground seesaw. The seesaw is stationary in the horizontal position and is 4.50 m long. Susan decides to jump off. Calculate the size of the unbalanced torque that now acts on the seesaw.


Homework Equations


torque= F * r (perpendicular distance?)
F=ma


The Attempt at a Solution


I'm not sure how to find the perpendicular distance from the line of action of the force to the axis of rotation. I think F would be 40*9.8=392 N but I don't know how to find the "r" value.
 
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  • #2
paperdoll said:
I'm not sure how to find the perpendicular distance from the line of action of the force to the axis of rotation. I think F would be 40*9.8=392 N but I don't know how to find the "r" value.
How far is she from the pivot of the seesaw? (You're given the full length of the seesaw.)
 
  • #3
Doc Al said:
How far is she from the pivot of the seesaw? (You're given the full length of the seesaw.)

It doesn't state the value in the question so I guess you are supposed to assume that she is half way. So 4.5/2=2.25 m
 
  • #4
paperdoll said:
It doesn't state the value in the question so I guess you are supposed to assume that she is half way. So 4.5/2=2.25 m
Yes, that's what I would assume. The axis of the seesaw is in the middle and she is sitting at one end.
 
  • #5


To find the perpendicular distance, also known as the lever arm, you need to measure the distance from the pivot point (axis of rotation) to the line of action of the force. In this case, the pivot point is the center of the seesaw and the line of action of the force is where Susan's weight is applied. Since the seesaw is 4.50 m long, the distance from the pivot point to the line of action of the force would be half of that, or 2.25 m. Therefore, the unbalanced torque would be 392 N * 2.25 m = 882 Nm. It is important to note that the direction of the torque would be clockwise, since Susan's weight is causing the seesaw to rotate in that direction. I hope this helps!
 

FAQ: Need help with a seesaw torque question.

1. What is torque?

Torque is a measure of the force that causes an object to rotate about an axis. It is calculated by multiplying the force applied to an object by the distance from the axis of rotation to the point where the force is applied.

2. How is torque related to a seesaw?

In a seesaw, the force exerted by each person on either side of the fulcrum creates a torque on the seesaw. The person who is further from the fulcrum exerts a greater force and therefore creates a greater torque, causing the seesaw to rotate.

3. What factors affect torque in a seesaw?

The factors that affect torque in a seesaw include the distance from the fulcrum to the point where the force is applied, the amount of force applied, and the angle at which the force is applied. The weight and position of the objects on the seesaw also play a role in determining the torque.

4. How can torque be calculated in a seesaw?

Torque can be calculated by multiplying the force exerted by a person on one side of the seesaw by their distance from the fulcrum, and then comparing it to the torque created by the person on the other side of the seesaw. The seesaw will be balanced if the torques are equal.

5. What are some real-world applications of seesaw torque?

Seesaw torque is used in many everyday objects, such as scissors, wrenches, and door handles. It is also an important concept in engineering, as it is used to design and understand the function of various machines and structures.

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