Chapter 4: Work, Power and Energy: Explaining the Causes of Motion Without Newton Flashcards
The product of force applied to a body and the amount of displacement the body undergoes in the direction of the force
-The means by which energy is transferred from one object or system to another
Work
Explain U=F(d)
U=F(d)
Where:
U=work done on an object
F= force applied to an object (N)
d=displacement of an object along line of action of the force (m)
Formula needed to calculate work done on an object
work/force*distance
What type of work is done by a force acting on an object if the object displaces in the same direction as the force?
ie throwing, jump takeoff
Positive mechanical work
What type of work is done by a force acting on an object when the object displaces in the opposite direction of the force acting on it?
ie catching, jump landing
Negative mechanical work
Positive or negative muscle work: ___a muscle contracts and its points of attachment move in the direction of the muscle pull
Positive muscle work
A type of of positive muscle work
Concentric contraction
Postive or negative muscle work: ____a muscle contracts and its points of attachment move in the direction opposite of the muscle pill
Eccentric contraction
What term defines the capacity to do work
Energy
What are the two forms of Mechanical energy?
Kinetic (motion) and Potential (stored)
Formula for kinetic energy
KE= 1/2*mv squared
Where:
KE= kinetic energy (kg/[m squared/s squared]=(kg[m/s squared]m)=Nm (Joule)
m=mass (kg)
v=velocity (m/s)
What are the two forms of Potential Energy (PE) ?
Gravitational PE and Strain PE
A type of PE whose energy is inherent due to an object’s position relative to the earth
Gravitational PE
A type of PE whose energy is stored due to an objeft’s deformation
Strain PE
Formula for Gravitational Energy
PE=mgh
Where:
PE=gravitational potential energy of an object (Nm=J)
mg=mass or weight (N)
h=elevation (height) above reference point (m) (ground or some other surfaces)
