Question

PLEASE FIND THE FORCES FOR EAXCH TABLE AND COMPLETE THE CALCULATIONS AND ANALYSIS SECTION. I REALLY NEED HELP WITH THIS!!!!!

Physics Lab # 7: Rotational Equilibrium

Objectives: When the forces acting on an object do not make the object rotate, the object is in a state of rotational equilibrium. In this online experiment you arrange forces that put an object into rotational equilibrium. You calculate the vector quantities of these forces, calculate the torques exerted by these forces, and calculate the net torque acting on the object. The objectives of this experiment are as follows:

1. To arrange forces on a rigid object so that it reaches rotational equilibrium

2. To calculate the torques exerted by forces on a rigid object

3. To test the hypothesis that an object in rotational equilibrium has no net torque acting on

   it

Theory: Recall that in Experiment 3 static equilibrium was studied. This was done by arranging forces on a force table so that they canceled each other and the objects stopped sliding. At this point, the net force on the objects was zero, and the acceleration was zero.

Here we study rotational equilibrium. This means that instead of studying linear acceleration caused by forces, we study angular acceleration caused by torques. An object that is in rotational equilibrium has zero net torque, and zero angular acceleration. Torque is defined as

τ =F⊥r.

That is, the torque on a rigid object is equal to the perpendicular force times the distance from the pivot point at which the force is acting. Note the perpendicular symbol on the force in this equation. In this online lab, we will only consider forces that are applied perpendicular to the rigid object, but in general it is possible to have a force applied at an arbitrary angle. (See Experiment 7 in the PHYS166/168 lab manual for details.)

An object in rotational equilibrium has a net torque of zero. In equation form this means

τTotal =∑τi.

iIt is important to note the direction of rotation that each torque is causing. Conventionally, torques that cause counterclockwise rotation are positive, while torques that cause clockwise ones are negative. This is just convention, and is analogous to choosing a direction as positive when adding force vectors. In that situation, you are free to choose any direction as positive, as long as you make sure that vectors pointing in opposite directions are subtracted. Here we want to ensure that torques that cause opposite rotations are subtracted.

Data Table:

Part A

Mass(kg)	Forces (N)	R (m)	Right or Left of center
15		1.00	left
5		0.50	left
10		1.25	right
20		0.25	right

Part B1

Mass(kg)	Forces(N)	R (m)	Right or left of the center
mA		2.00	left
mF		1.25	left
20		1.75	right
20		1.25	right
20		0.50	right
5			right

Part B2

Mass(kg)	Force(N)	R (m)	Right or Left of the center
mA		1.00	left
mF		0.25	left
15		2.00	right
5		0.50	right

Calculations and Analysis:

1. Calculate the torque that each mass exerts on the seesaw in Part A.

2. Calculate the sum of the torques in Part A. Does this value agree with what you expect?

   Explain why or why not.

3. Calculate the total mass applied to the left and the right side of the seesaw in Part A. Are

   the values equal? Does this agree with what you expect? Why or why not?

4. Write an equation for the sum of the torques in Part B1.

5. Write another equation for the sum of the torques in Part B2.

6. After writing the equations in questions 4 and 5, you have two equations and two

   unknowns, m​ and m​ . Solve these two equations for the unknown masses.

7. What is one way you can use the PHET program to check the masses you calculated in question 6? Test your method and report whether the results agree with what you found.

8. Can you make the see-saw balance with the kids (20 kg & 30 kg) on one side of the pivot, and the parents (60 kg & 80 kg) on the other side? If you were able to get to that state, then write down their individual positions as your answer!

R (m) is 0.5 for the 5kg in Part B1

This is all the information there are for this lab.

Answer 1