Calculating forces involved in seesaw motion

In summary, the conversation discusses a seesaw with specific dimensions and weights placed at each end. The question is raised about how to calculate the angular velocity and acceleration of the seesaw when it is released, as well as the time it takes for the heavier end to hit the ground. The concept of torque is also mentioned, and it is suggested to draw a free body diagram and sum moments to solve the problem. The conversation also brings up the scenario of a child sitting on the seesaw and the force they exert on the ground to bring them to a certain height. The solution involves considering the moment of inertia and using the parallel axis theorem.
  • #1
epka05
1
0
Let's say i have a plank of wood (seesaw) 2in x 8in x 12ft with approx. mass of 50lbs. The fulcrum is 2.36ft high and is in the center of the board. There is 45lb placed on one end and 22 lb place on the other end. The 22lb end is secured to the ground ready for release. The 45lb-end is 4ft 6in off the ground.

I know you would have to use the tau=I*α. I also know that i have to get the total tau (torque) by the summation of the moments due to the weights.

Neglecting friction how would the angular velocity and angular acceleration of the seesaw be determined when it is released? Also how would one calculate time it takes for the 45-end to hit the ground?

Now let's say that there is a kid with a weight of 45lb instead of the 45lb weight what would be the force which he exerts on the ground to bring him to the height of 4ft 6in?
Thanks
 
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  • #2
Let's take the real easy question first. At the moment of release, the angular velocity is zero because nothing is moving. Bingo! one item down.

Presumably you can draw a FBD and sum moments, so we will assume that you can get the left side of the moment sum equation. The moment of inertia has to be considered as the distributed MMOI of the plank about the pivot, plus the MMOI of two concentrated masses, one at each end. You know the weights for each item, so convert these into masses, use the parallel axis theorem, and combine the whole thing to get I. From there get alpha at t=0.

This should get you started. See if you can't take it from there.
 

FAQ: Calculating forces involved in seesaw motion

1. How do you calculate the forces involved in seesaw motion?

The forces involved in seesaw motion can be calculated using the principle of torque. Torque is defined as the force applied perpendicular to a lever arm multiplied by the length of the lever arm. In a seesaw, the two forces acting on the seesaw are the weight of each person sitting on it, and the distance from the pivot point to the center of mass of each person. By multiplying these forces by their respective distances from the pivot point, you can calculate the torque exerted by each person on the seesaw. The seesaw will be in equilibrium when the torques on each side are equal.

2. What is the significance of calculating the forces involved in seesaw motion?

Calculating the forces involved in seesaw motion is important because it helps us understand the physics behind the motion. By understanding the forces involved, we can predict how the seesaw will move and make adjustments to achieve balance. It also allows us to analyze the safety of the seesaw and make sure that it can support the weight of the users without tipping over.

3. How does the distribution of weight on a seesaw affect the forces involved?

The distribution of weight on a seesaw affects the forces involved by changing the distance from the pivot point to the center of mass of each person. The greater the distance, the more torque is exerted. This means that a heavier person sitting closer to the pivot point can have the same amount of torque as a lighter person sitting further away from the pivot point. Therefore, the distribution of weight can significantly impact the balance of the seesaw.

4. Can friction affect the forces involved in seesaw motion?

Yes, friction can affect the forces involved in seesaw motion. Friction is a force that opposes motion, and it can act on the seesaw at the pivot point. This can cause the seesaw to not move as freely as it would without friction, and it can also impact the balance of the seesaw by adding an additional force acting on one side of the seesaw. Therefore, friction should be considered when calculating the forces involved in seesaw motion.

5. Are there any safety considerations when calculating the forces involved in seesaw motion?

Yes, there are safety considerations when calculating the forces involved in seesaw motion. It is important to make sure that the seesaw can support the weight of the users without tipping over. This can be achieved by properly distributing weight on the seesaw and making sure that the seesaw is made of strong and sturdy materials. It is also important to consider the impact of external forces, such as wind or uneven ground, on the seesaw's balance. By taking safety into account when calculating the forces involved, we can ensure a safe and enjoyable experience on the seesaw.

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