ID:______NAME:______________________________________________________DATE:_______________________________CLASS:________

Chapter 11: Torque Notes POGIL #1REMEMBER: Throughout this paper, you will see some symbols. The “stop sign” means STOP and check with a teacher before continuing. The “key” means THIS IS A KEY POINT, PAY ATTENTION!

11.1: TORQUE - DIRECTIONS: Use the information in the boxes to answer the following questionsEvery time you open a door, turn on a water faucet, or tighten a bolt with a wrench, you exert a turning force called TORQUE.Torque is different than force: torque makes an object turn; net force makes an object accelerate.

1. What are some everyday examples (that are NOT listed above) in which you use torque to complete a task?

When the force is perpendicular, the distance from the turning axis to the point of contact is called the lever arm.

When a perpendicular force is applied to a door, the lever arm is the distance between the doorknob and the edge with the hinges. (see image to the right)

2. Look the formula above for TORQUE. Which of the following produces the greatest torque?

a. Small force, short lever armb. Large force, small lever armc. Small force, long lever armd. Large force, long lever arm.

3. CIRCLE ONE: Torque is (directly, inversely) proportional to the perpendicular

force.

4. CIRCLE ONE: Torque is (directly, inversely) proportional to the lever arm.

5. COMPLETE THE SENTENCE: The same torque can be produced by a large force with a short lever arm, or a small force with a ______________________________________________________.

6. Write #5 in exaggerated equation form (bigger/smaller symbols…force is represented by ‘F’ and lever arm is represented by ‘LA’ )

7. Suppose you try to push open the door below 3 times. Hinge is on the left; doorknob on the right, just like our classroomdoors!

1. First, you push by the HINGE (see then‘x’).

2. Then, you push in the middle. 3. Finally, you push by the handle.

(**TRY this on the classroom doors!!!)a. In which scenario is the lever arm the SHORTEST?

_________b. In which scenario is the lever arm the LARGEST?_________

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c. In which scenario is it most difficult to open the door? _________d. So, in which scenario do you have to exert the MOST FORCE?

_______________________e. In which scenario is it easier to open the door? _________f. So, in which scenario do you have to exert the LEAST FORCE?

_______________________When the force is perpendicular, the distance from the turning axis to the point of contact is called the lever arm.

If the force is not at right angle to the lever arm,then only the perpendicular component of the force will contribute to thetorque.

Although the magnitudes of the applied forces are the same in each case, the torques are different.

8. Why do you think the torques get progressively larger in the above scenarios –notice any trends? Let’s see how well you interpreted by answering 8a & 8b…

a. What is different from scenario 1 to scenario 2?

b. What is different from scenario2 to scenario 3?

9. Can the same force produce different amounts of torque? EXPLAIN:

10. Can the same torque be exerted from different forces? EXPLAIN:

11. If you cannot exert enough torque to turn a stubborn bolt, would more torque be produced if you fastened a length of rope to the wrench handleas shown? EXPLAIN:

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*Check and CORRECT your answers to #11 in your textbook – seethe yellow box on pg 152; answers are at bottom of page…See

teacher for clarification if needed!*11.3: TORQUE & CG - REMEMBER - The Leaning Tower of Pisa does nottopple over because its CG lies above its base…if the CG extendedBEYOND the base it would topple…but WHY? The answer is due to

TORQUE.

12. When the CG is not over the area of support, what force produces a torque that causes toppling?

11.2: BALANCED TORQUES - DIRECTIONS: Use the information in the boxes to answer the following questions

Weight alone does not produce rotation—torque does. When balanced torques act on an object, there is no change

in rotation. 2 kids can balance a see-saw even when their weights are not

equal! o A pair of torques can balance each other. o Balance is achieved if the torque that tends to

produce clockwise rotation (by the boy) equals thetorque that tends to produce counterclockwiserotation (by the girl.)

Torque counterclockwise = Torque clockwise

(Force x Lever Arm) counterclockwise = (Force x Lever Arm ) clockwise

13.Calculate the girl’s torque:a. What is the girl’s weight? (this is the Perpendicular Force)___________________________b. What is the girl’s DISTANCE from the FULCRUM/TURNING POINT? (This is the Lever

Arm)_____________c. Calculate the girl’s torque: *Show all work; the unit for torque is the Newton Meter ( Nm)

14.Calculate the boy’s torque:a. What is the boy’s weight? (this is the Perpendicular Force)___________________________b. What is the boy’s DISTANCE from the FULCRUM/TURNING POINT? (This is the Lever

Arm)_____________c. Calculate the boy’s torque: *Show all work; the unit for torque is the Newton Meter ( Nm)

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15. How does the girl’s torque compare with the boy’s torque? What do you notice:

16. Do the math! What is the weight of the block hung at the 10-cm mark? *REMEMBER – The lever arm is the distancefrom the TURNING POINT to the PERPINDICULAR FORCE –BE CAREFUL! SHOW ALL WORK:

*Check and CORRECT your answer to #16 in your textbook – see pg 153 …See teacherfor clarification if needed!***FYI: Scale balances that work with sliding weights are based on balanced torques, not balancedmasses. The sliding weights are adjusted until the counterclockwise torque just balances theclockwise torque. We say the scale is in rotational equilibrium.

11.2 – Balanced Torques WEBQUEST - Balancing Act PhET Lab(2012)

Introduction: Ever had to carry a single heavy sack of books or groceries with one hand?

o What happens to your body to allow you to do this? o How is your body different when you have to carry TWO sacks, one on each side?

How about the classic, teeter totter (see saw)? o Can your successfully totter/ see saw with someone heavier than you? o How? o Many people think that weight is all that matters when you balance something…

but that downward force (weight) is only a part of the situation. You will be investigating balanced torques in this web quest.

Procedure:1.Go to http://phet.colorado.edu/en/simulation/balancing-act , or google “PHET Balancing

Act”

2.Click on the picture:

3. Take 5-10 minutes to play with the simulation. There are 3 tabs at the top - Intro, Balance Lab, and Game. Try all 3. Go ahead. Play. Have fun. Learn. Pay close attention to tab 2 – Balance Lab. That is what you will be doing later in this activity!

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4.Is there more than one way to get two objects withidentical masses to balance? How?

5.Next, try to get two objects of different masses tobalance. Try to describe at least 2 different ways thatyou were able to balance them and draw them below. **Make sure you label themasses and the distance to each mass from the center (pivot point). (HINT– click RULER & LEVEL)**

a.

b.

6. Look at the image below. The, test your prediction in the simulation and fix any errors. a. PREDICTION:

i. Where would you need to place the floating fire extinguisher to balance the system? Draw your prediction below.

b. TEST IT! (Go to “Balance Lab portion, set it up as shown, and click “Remove Supports”)

i. Was your predication right? ____________ii. Why or why not?

7. Look at the kids on the see-saw. a. PREDICTION:

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i. Will this balance?____________ii. Why or why not?

b. TEST IT! (Go to “Balance Lab portion, set it up as shown, and click “Remove Supports”) i. Was your predication right? ____________

ii. Why or why not?

8. The box on the left is 15 kg and the box on the right is 60 kg

a. PREDICTION: i. Will this balance?____________

ii. Why or why not?

b. TEST IT! (Go to “Balance Lab portion, set it up as shown, and click “Remove Supports”) i. Was your predication right? ____________

ii. Why or why not?

c. How could you CHANGE this so that the see saw would balance? Draw your prediction here:

d. TEST IT – Was your prediction correct?_____ Draw what you observed here, and make any necessarycorrections:

9. The girl is 30 kg. Where would you have to place the 60 kg woman inorder to balance the see-saw?

a. CALULATE & DRAW your prediction:

b. TEST your prediction. Were you correct? _______c. If you need to make any corrections, do so now:

10. Finally, determine the mass of each of the mystery objects. SHOW ALL WORK!

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