MOMENT OF FORCE (TORQUE) Elisa A. Valladolid Ernesto Rondon High School 19/04/10 4 th year High...
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Transcript of MOMENT OF FORCE (TORQUE) Elisa A. Valladolid Ernesto Rondon High School 19/04/10 4 th year High...
![Page 1: MOMENT OF FORCE (TORQUE) Elisa A. Valladolid Ernesto Rondon High School 19/04/10 4 th year High School.](https://reader035.fdocuments.net/reader035/viewer/2022070400/56649ece5503460f94bdb3ef/html5/thumbnails/1.jpg)
19/04/10
MOMENT OF FORCE (TORQUE)
Elisa A. ValladolidErnesto Rondon High School
4th year High School
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OBJECTIVE
Describe the moment of force in terms of it’s turning effects.
State the principle of moments for a body in equilibrium.
Apply principle of moments in everyday life.
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Why moment of force/ torque?
Have you experienced playing seesaw?Can you play it alone?How does it turns?
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Which is easiest way of opening the door?
(Demonstration; A. Opening the door by pulling/ pushing from the center . B. Opening the door through the knob.
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Why?
(Share your answer with your seatmates)
( Explain why you choose A or B )
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Situation A: A greater force is needed if
we open the door near the hinge.
Situation B: Less force or effort is
needed if we pull furthest from the hinge.
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How does the door make it turn?
(the turning effect on the door is in the hinge, which a fixed
point also called the pivot and the turning effect of force
is also called Moment of Force /Torque)
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What is the amount of moment of force/Torque?
Perform Activity no. ___ (Moment about a fixed pivot)
( Each group have a prepared set-up, and an activity sheet, they have to prepare their output in manila paper and present in class.)
Microsoft Office Word Document
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Principle of moments
Pivot/ fulcrum
F
d
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Again, turning effect of a force is called moment of force or torque.
Moment of a force = force x perpendicular
distance from the pivot = F x d SI unit is Newton-meter (N m)
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Principle of moments
F F1 F2
d1 d2
Pivot/fulcrumAnticlockwise moment
Clockwise moment
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Principle of moments: When an object is in
equilibrium, the sum of clockwise moments about any point is equal to the sum of anticlockwise moments about the same point.
Anticlockwise moment = Clockwise moment
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Any Questions?
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Evaluation
1. What is the name given to turning effect of a force about a pivot?
a. inertia b. moment c. pressure d. resultant
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CORRECT!
Congratulations
The turning effect of force is called moment of force or torque.
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2. It is better to use a longer spanner to undo a nut because
a. less force is exerted be the user.
b. less moment is applied on the spanner.
c. less friction is present. d. greater inertia is present.
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CORRECT!
Congratulations
Moment of force = force x distance with a greater distance it lessen the moment.
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3. A door requires a minimum moment of 32.5 N m to open it,
hingehandle
X
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What is the minimum distance between the handle and the hinges, if the door is to be pulled with a force on the handle not greater than 50 N?
a. 0.33 m b. 0.25 m c. 0.65 m d. 1.54 m
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CORRECT!
Congratulations
Moment of force = F x d 32.5 = 50 N x d 32.5 = d 50 0.65 m = d
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4. The diagram below shows a light rod with weights hanging from it. The system is not in equilibrium. What is the moment required to bring the system into equilibrium?
5n
4n
0.8m 1.5 m
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moment direction a. 2 Nm clockwise
b. 6 Nm anticlockwise
c. 4 Nm clockwise d. 2 Nm anticlockwise
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CORRECT!
Congratulations
Anticlockwise moment = clockwise moment F x d = F x d 5 N x .8 m = 4 N x 1.5 m
4Nm= 6 NmTo make it in equilibrium need 2nm from theAnticlockwise moment.
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5. A light rod is in equilibrium under the action of the force as shown below. What is the magnitude of the force F?
20 N F 12 N
2m 1m 1 m
a. 28 N b. 8 N c. 16 N d. 4 N
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CORRECT!
Congratulations
Anticlockwise moment = clockwise moment F3 x d3 = F1 x d1 + F2 x d2
20 N x 2m = F x 1 m + 12 N x 1 m 40 Nm = 1 F + 12 Nm 40 Nm -12 Nm = 1 F 28 Nm = 1 F 1m 1 28 N = F
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Assignment
A. What is the center of gravity?
B. How is the center of gravity related to stability?
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Sorry!
That was the wrong answer