Torque - CPO Science
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Transcript Torque - CPO Science
Key Questions:
What is torque?
How do we calculate torque?
Performance Objectives
Measure forces and distances in a
simple machine.
Calculate torque.
Apply the concept of mechanical
advantage to levers.
Build three classes of levers.
Lever Assembly
SAFETY NOTE:
WATCH for FALLING weights on bare
toes or sandals or table tops!
DO not place the fulcrum higher than
hole 3 of stand!
Torque
Levers use torque to lift or move objects.
Torque is a force applied over a distance that
causes ROTATION to occur.
Torque is measured in Newtonmeters (Nm)
Review of levers
Input Force
x Length of
Input Arm
=
Output Force
x Length of
Output Arm
Force x Distance = Force x Distance
Torque
=
Force
X
Distance
An Example of Torque
Calculate the
torque created
when opening
the door.
1. Set up the balanced lever
2. Measure Forces and
3. Calculate input/output torques
Calibrate the spring scale
Data
Torque and direction
If more than one torque acts on an object, the torques are
combined to determine the net torque.
If the torques tend to make an object spin in the same
direction (clockwise or counterclockwise), they are added
together.
If the torques tend to make the object spin in opposite
directions, the torques are subtracted.
Torques causing counterclockwise rotation are positive
and torques causing clockwise rotation are negative.
Forces and Machines
The variables in a simple machine
can be adjusted make work easier
or resist forces on purpose.
Consider two levers:
Forces and Machines
The advantage the simple machine gives to
the user can be calculated.
A machine approaches a mechanical
advantage of 1, when output forces roughly
equal input forces.
Mechanical Advantage
mechanical
advantage
Input force (N)
MA = Fo
Fi
Output force (N)
Mechanical advantage
What is the mechanical advantage of
this new lever?
Torque and mechanical advantage
What’s the mathematical relationship
between torque and mechanical
advantage?
MA = Output Torque ÷ Input Torque
Build different levers…
Three Classes of Levers
First Class - fulcrum
between Input and output
Second Class – output
between fulcrum and input
Third Class – input between
fulcrum and output
Levers and the human body
Your body contains
muscles attached to
bones in ways that act
as levers.
Here the biceps
muscle attached in
front of the elbow
opposes the muscles
in the forearm.
Can you think of other muscle
levers in your body?
Mobiles are levers!
GREAT STEM project!
Outcomes
Use science
Think scientifically
Communicate technical ideas
Teach all students
Be science conscious NOT
science phobic
What questions do you
have about Torque or
Mechanical Advantage?