Name: Date:
Student Exploration: Torque and Moment of Inertia
Vocabulary: angular acceleration, fulcrum, lever, moment of inertia, Newton’s second law,torque,
weight
Prior Knowledge Question (Do this BEFORE using the Gizmo.)
During recess, Tom and his little sister Marcie want to play on the see-saw. Tom is quite a bit heavier
than Marcie. Where should they sit so the see-saw is balanced? Sketch their positionson the image
below.
Explain your reasoning As long as you set
both of them an equal distance fromthe
fulcrum.
Gizmo Warm-up
The Torque and Moment of Inertia Gizmo™ shows a see- saw,
which is a type of lever. The see-saw can hold up to eight objects.
To begin, check that the Number of objects is
2. Check that the mass of object A is 1.0 kg and the mass ofobject
B is 2.0 kg. The two objects are equidistant from the triangular
fulcrum that supports the lever.
1. Click Release. What happens? B weighs down the seesaw
2. Click Reset. Without changing the masses, experiment with different positions of objects
A and B by dragging them around.
Can you create a scenario in which object A goes down and object B goes up?
Explain: _When b is closer to the end
3. Can you create a scenario in which object A perfectly balances object B? When bothare
create an equilibrium
, Activity A: Get the Gizmo ready:
Principle of the • Click Reset. Turn on Show ruler.
lever • Check that object A is 1.0 kg and B is 2.0 kg.
Question: How can you use a light object to balance a heavy object?
1. Explore: Experiment with the Gizmo to see how you can balance a heavy object with a lightobject.
What do you notice about the distances of each object from the fulcrum?
They
2. Gather data: For each mass and location of object A, find a location for object B so it perfectly
balances object A. You can change the mass of object A by typing the mass intothe text box and
hitting “Enter” on your keyboard. Leave the mass of object B the same (1 kg) in each experiment.
Include all units in the table.
Object A Object A Object B Object B Object A Object B
mass location mass location m×d m×d
1.0 kg -0.4 m 1.0 kg .4 .4 1
2.0 kg -0.4 m 1.0 kg .4 .8 2
3.0 kg -0.4 m 1.0 kg .4 1.2 3
4.0 kg -0.4 m 1.0 kg .4 1.6 4
3. Analyze: What patterns do you notice in your data? They are exponentially getting greaterby a
factor of of .4
4. Calculate: Fill in the last two columns by multiplying each object’s mass by its distance fromthe
fulcrum. The units are kg·m. (Note: The distance d is always a positive number.)
What do you notice? They are constant with object mass A
5. Generalize: In general, how can you calculate the distance of object B from the fulcrum so that it
balances object A? By measuring and creating an equilibrium
6. Apply: Suppose you wanted to lift a heavy rock with a lever. Would you place the fulcrumnear
the rock or near the part of the lever where you are pushing? Explain.
Closest to the fulcrum because the weight that is basically distributed over a small areaclosest to the
fulcrum rather the further you go the harder it is to lift.
Student Exploration: Torque and Moment of Inertia
Vocabulary: angular acceleration, fulcrum, lever, moment of inertia, Newton’s second law,torque,
weight
Prior Knowledge Question (Do this BEFORE using the Gizmo.)
During recess, Tom and his little sister Marcie want to play on the see-saw. Tom is quite a bit heavier
than Marcie. Where should they sit so the see-saw is balanced? Sketch their positionson the image
below.
Explain your reasoning As long as you set
both of them an equal distance fromthe
fulcrum.
Gizmo Warm-up
The Torque and Moment of Inertia Gizmo™ shows a see- saw,
which is a type of lever. The see-saw can hold up to eight objects.
To begin, check that the Number of objects is
2. Check that the mass of object A is 1.0 kg and the mass ofobject
B is 2.0 kg. The two objects are equidistant from the triangular
fulcrum that supports the lever.
1. Click Release. What happens? B weighs down the seesaw
2. Click Reset. Without changing the masses, experiment with different positions of objects
A and B by dragging them around.
Can you create a scenario in which object A goes down and object B goes up?
Explain: _When b is closer to the end
3. Can you create a scenario in which object A perfectly balances object B? When bothare
create an equilibrium
, Activity A: Get the Gizmo ready:
Principle of the • Click Reset. Turn on Show ruler.
lever • Check that object A is 1.0 kg and B is 2.0 kg.
Question: How can you use a light object to balance a heavy object?
1. Explore: Experiment with the Gizmo to see how you can balance a heavy object with a lightobject.
What do you notice about the distances of each object from the fulcrum?
They
2. Gather data: For each mass and location of object A, find a location for object B so it perfectly
balances object A. You can change the mass of object A by typing the mass intothe text box and
hitting “Enter” on your keyboard. Leave the mass of object B the same (1 kg) in each experiment.
Include all units in the table.
Object A Object A Object B Object B Object A Object B
mass location mass location m×d m×d
1.0 kg -0.4 m 1.0 kg .4 .4 1
2.0 kg -0.4 m 1.0 kg .4 .8 2
3.0 kg -0.4 m 1.0 kg .4 1.2 3
4.0 kg -0.4 m 1.0 kg .4 1.6 4
3. Analyze: What patterns do you notice in your data? They are exponentially getting greaterby a
factor of of .4
4. Calculate: Fill in the last two columns by multiplying each object’s mass by its distance fromthe
fulcrum. The units are kg·m. (Note: The distance d is always a positive number.)
What do you notice? They are constant with object mass A
5. Generalize: In general, how can you calculate the distance of object B from the fulcrum so that it
balances object A? By measuring and creating an equilibrium
6. Apply: Suppose you wanted to lift a heavy rock with a lever. Would you place the fulcrumnear
the rock or near the part of the lever where you are pushing? Explain.
Closest to the fulcrum because the weight that is basically distributed over a small areaclosest to the
fulcrum rather the further you go the harder it is to lift.
