Work, Energy, and Power (Test 2) Flashcards
What is Mechanical Work
A quantity that describes the extent to which a force can move (accelerate) an object.
U = Fd = ∆E
What is Mechanical Energy
The ability to perform work.
U = ∆KE + ∆GPE + ∆SE
When work is done, what happens to mechanical energy
It changes
What is power
The rate at which mechanical work can be performed
P = U/t = Fv
What are the three kinds of Mechanical energey
Gravitational Potential Energy
Kinetic Energy
Strain Energy
What is Kinetic Energy
Energy due to motion
KE = 1/2mv²
What is Gravitational Potential Energy
Energy due to height
PE = wt x h = mgh
What is Spring Energy
Energy due to deformation
SE = 1/2kx²
(k = stifness, x = amount stretched)
When gravity is the only external force, is Mechanical Energy conserve
Yes
We need to be familiar with the Force-Velocity Curve.
Look at the picture
So how does one train for power
by doing fast eccentric muscle action
What is concentric contraction
Contraction of the muscle while the muscle body is shortening
What is eccentric contraction
Contraction of the muscle while the muscle body is lengthening
What is positive work
when the direction of force is the same as the displacement of the object. (concentric contraction)
What is negative work
When the direction of force is in the opposite direction of the displacement of the object. (Eccentric contraction)
