Saga of the seesaw

You walk to your old elementary school playground and see a seesaw sitting all by itself.

The board is 10 meters long and has a mass of 20 kg.

1. What is the force exerted on the seesaw by the fulcrum?
2. What is the torque exerted on the seesaw by the fulcrum?
3. Is the seesaw in static equilibrium?

You come back the next day and find that someone has placed a box of mass m = 10 kg on one side of the board.

You decide to bring the seesaw back into a horizontal position by pushing down on the other end.

1. How hard must you push down on the other end of the board in order to maintain static equilibrium?
2. What is the torque you are exerting around the fulcrum?
3. What is the force exerted on the board by the fulcrum?

The next day, you come back and find that the box has been moved closer to the fulcrum.

1. How hard must you push down on the other end of the board in order to maintain static equilibrium?
2. What is the force exerted on the board by the fulcrum?

When you return the next day, you find that the playground has been vandalized! Someone has cut off a portion of the board!

1. How hard must you push down on your end of the board in order to maintain static equilibrium?
2. What is the force exerted on the board by the fulcrum?

You report this crime to the school authorities, who repair the seesaw. The next time you visit, the board is back to its normal size and mass. You decide to be a little different and push your end of the board at an angle of theta = 30 degrees as shown.

1. What is the size of the force you must exert in order to maintain static equilibrium?
2. What is the torque around the fulcrum which you are applying to the board?
3. (Be careful -- this one might be tricky) What is the force exerted on the board by the fulcrum?

Copyright © Michael Richmond. This work is licensed under a Creative Commons License.