Torque and Center of Gravity Flashcards
How should forces be applied if you are pushing someone by their shoulders
Perpendicular
T/F Systems rarely move in purely linear motion
True
In which two situations does rotation occur
- When the system is restricted to move around a fixed axis
- Around the center of gravity
What is the turning effect produced by?
Torque
In our body, what creates torque about our joints?
Our muscles
What is a centric force
A force going through the point of rotation
What is an eccentric force
A force that does not go through the point of rotation
Which type of force causes linear motion
Centric force
Which type of force creates rotation
Eccentric force
What is a force couple?
Two forces equal in size but opposite in direction and noncolinear
What is the resultant of a force couple?
Zero
T/F An eccentric force can cause changes in both linear and angular motion of an object
True
What type of force only causes a change in the angular motion of an object
A force couple
What two factors does torque depend on?
- The magnitude of externally applied force
- The force arm/ moment arm/ lever arm
What is the definition of a lever arm
The perpendicular distance between the axis of rotation and the line of action of the applied force
What is the equation for torque
T=Fd
What does the moment arm change with?
The joint angle
T/F The same force cannot produce different torques with a change in moment arm
False, the same force will produce different torques
What is the direction of torque associated with?
With the rotation that it causes
If a torque that causes counterclockwise rotation what sign will it be
Positive
If a torque causes clockwise rotation what sign will it be
Negative
What is net torque acting on an object the sum of
All external torques acting on it
Define Center of Gravity
The point around which all of the torques sum to zero
T/F It is possible to have the COG outside of the body?
True
Why is it possible to jump higher with only open hand reaching overhead?
Because the COG in the body is lower
Why could one high jumper jump higher than another with the same stature and same athletic ability?
Because of better technique
