Physics Test #3
SI Unit for Kinetic and Potential Energy
J
SI Unit for Work (W)
J
Define: Resistive Force
Keeps an object from moving. This frictional force is called STATIC FORCE; Fs
What is Newton's Third Law?
Law of Action and Reaction
What is Newton's Second Law?
Law of Force
What is Newton's First Law?
Law of Inertia
Define: Kinetic Energy
Moving energy
All forces are measured in
N
SI Unit for Force (F)
N
Can the kinetic energy of an object to negative?
No because mass is scalar and velocity is squared so it's always positive
SI Units for µs and µk
No units
Define: Fn
Normal Force
Define Newton's First Law
Objects at rest will stay at rest and objects in motion will stay in motion unless acted on by an unbalanced external force
Potential Energy Equation
PEg = mgh
Define: Contact Force
Pushes/Pulls; Force acting with physical contact
Types of Friction
Resistive Force and Retarding Force
Define: Retarding Force
Slows an object in motion down. This force is called KINETIC FORCE; Fk
Define: Gravitational Potential Energy
Stored Energy
Define: Potential Energy
Stored Energy
In the work energy equations in the y-direction the sin is usually ____, unless stated otherwise
sin 90° = 1
Work energy root equation in x-direction #2
W = mad; ma = F
Work energy root equation in y-direction #2
W = mgd; mg = F
Mass is not a ____
force
Weight is a _____
force
1J equal how many kg²/s²
1 J = 1 kgm²/s²
Define: Friction
A force that opposes motion for the object to move or for the object to stop moving; Fapplied > Ffriction
Example of Field Force
A soccer ball at rest
Example of Contact Force
A soccer ball being kicked
Why is µs > µk?
Because it's harder to get something to start moving from rest than it is to slow down
Kinetic Energy Work Theorem Root Equation
Fd = 1/2mv²
Kinetic Energy Work Theorem Expanded Equation
Fd(cosθ) = 1/2mvf² - 1/2mvi²
Normal Friction equation; Fn
Fn = mg
Define Newton's Third Law
For every action there is an equal and opposite reaction
Define: Field Force
Force acting with physical contact; Force of Gravity, Magnetic Force, and Static electricity
Define: Fg
Force of Gravity
Types of Potential Energy
Gravitational Potential Energy and Elastic Potential Energy
What do the coefficients of friction tell you?
How much friction there is between an object and the surface it is in contact with
Define Newton's Second Law
The amount of force acting on an object is directly proportional to the object's mass mulitplied by its acceleration; F = ma
Which is usually greater, the maximum force of static friction, or the force of kinetic friction?
The force of static friction is usually greater because it's harder to get a object to move from rest than it is to get an object to move when it's already in motion
What are Free Body Diagrams used for?
These are used to show the direction of the forces acting on an object
Forces are ______
Vector
Work energy root equation
W = Fd
Work energy root equation in x-direction #1
W = Fd(cosθ)
Work energy root equation in y-direction #1
W = Fd(sinθ)
Mass doesn't ______, while weight does
change
In the work energy equations in the x-direction the cos is usually ____, unless stated otherwise
cos 0° = 1
Work is a type of
energy
Fn and Fg are
equal in magnitude but opposite in direction (Object is in equilibrium)
SI Unit for mass (m)
kg
SI Unit for distance (d)
m
SI Unit for Speed (V)
m/s
SI Unit for acceleration (a)
m/s²
SI Unit for gravity (g)
m/s²
Force of Friction ALWAYS _______ the applied forces
opposes
For work to be done, the components of the force and the distance must be ____ to one another
parallel
SI Unit for time (t)
s
Equation for Weight
w = mg
F = mg is in what direction?
y-direction
What is the coefficient of Kinetic Friction?
µk = Fk/Fn = Fk/mg
What is the coefficient of Static Friction?
µs = Fs/Fn = Fs/mg
