Go tohttps://phet.colorado.edu/en/simulation/balancing-act.

7. If 10 kg is placed at .75m to the left of the pivot and 15 kg is place 1.0m to the right of the pivot, where should a 5 kg brick be placed in order to balance the see-saw? Show your calculations and verify with the simulation.

8. Starting with the scenario in the previous question (assuming it is balanced), if a 30 kg climbs on and sits .25m to the left of the pivot, where should a single 5 kg brick be placed to achieve equilibrium? Do you need to include all the objects that are currently on the see-saw in your calculation? Explain. Show your calculations and verify with the simulation.

Part D: Unknown masses

9. Clear off the seesaw. Scroll through the masses to the unknowns (marked A through H). Choose one of them and put it somewhere on the right half of the seesaw. Use one of the bricks (or people) of known mass to balance out the unknown mass (trial and error is OK), and record the values ofm_L,r_L, andr_R in the table below. Please do t h i i s for three more unknown masses. You may have to use different bricks/people to balance them.

mL (kg)	rL (m)	mR (kg)	rR (m)

Table 2: Datafor unknown masses.

10. For each of the four unknown masses you chose, use the equilibrium condition that the net torque must be 0 to calculate the unknown mass. Show calculations, with units, in the space below.