mechanical advantage and the inclined plane: more practice
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Mechanical Advantage and the Inclined Plane: More Practice
Mechanical Advantage and the Inclined Plane: More Practice
Mechanical Advantage and the Inclined Plane: More Practice
Mechanical Advantage and the Inclined Plane: More Practice
Mechanical Advantage and the Inclined Plane: More Practice
Levers and Torque: Student Learning GoalThe student will be able to solve problems
involving torque, force, load-arm length, and effort-arm length as they relate to levers (C2.5).
Levers and Torque
SPH4C
The Lever
A lever is a rigid bar that can rotate freely around a support called a fulcrum.
Torque
When a force causes a rigid body to rotate, we say that a torque has been applied.
Torque is defined as the turning effect.
Torque
Torque (T) increases as force (F) increases and also increases as distance (d) from the fulcrum increases:
Torque
Torque (T) increases as force (F) increases and also increases as distance (d) from the fulcrum increases:
FdT
Torque
Torque (T) increases as force (F) increases and also increases as distance (d) from the fulcrum increases:
Torque has units of N m.
FdT
Torque: Example
A force of 84 N is used to turn a wrench of length 25 cm. What was the torque on the wrench?
Torque: Example
A force of 84 N is used to turn a wrench of length 25 cm. What was the torque on the wrench?
Torque: Example
A force of 84 N is used to turn a wrench of length 25 cm. What was the torque on the wrench?
?:
25.025
84:
TUnknown
mcmd
NFGivens
Torque: Example
A force of 84 N is used to turn a wrench of length 25 cm. What was the torque on the wrench?
?:
25.025
84:
TUnknown
mcmd
NFGivens
Torque: Example
A force of 84 N is used to turn a wrench of length 25 cm. What was the torque on the wrench?
?:
25.025
84:
TUnknown
mcmd
NFGivens
mNmNTSolve
FdTSelect
21)25.0)(84(:
:
Load torque and Effort torqueFor any lever there are two torques: the load
torque (TL) and the effort torque (TE):
EEE
LLL
dFT
dFT
dL and dE are referred to as the load arm and effort arm, respectively.
Static Equilibrium
If the load torque equals the effort torque, the lever is in static equilibrium.
Static Equilibrium
If the load torque equals the effort torque, the lever is in static equilibrium.
EL TT
EELL dFdF
Static Equilibrium: ExampleWhat force does your bicep need to exert to hold a
weight of 134 N (30 lbs)?
Remember that the human forearm is a lever.
Static Equilibrium: ExampleWhat force does your bicep need to exert to hold a
weight of 134 N (30 lbs)?We will ignore the weight of the forearm itself.
?
:
05.05
3.030
134
:
E
E
L
L
F
Unknown
mcmd
mcmd
NF
Givens
Static Equilibrium: ExampleWhat force does your bicep need to exert to hold a
weight of 134 N (30 lbs)?
?
:
05.05
3.030
134
:
E
E
L
L
F
Unknown
mcmd
mcmd
NF
Givens
Static Equilibrium: ExampleWhat force does your bicep need to exert to hold a
weight of 134 N (30 lbs)?
?
:
05.05
3.030
134
:
E
E
L
L
F
Unknown
mcmd
mcmd
NF
Givens
N
m
mNFSolve
Fd
dFdFdFSelect
E
EE
LLEELL
80405.0
3.0134:
:
Or approximately 800 N
More Practice
Levers and Torque Lab Activity