physics - unit 3: semester 1

what are the two types of main forces?

contact and field forces

gravity >

a long range force that is also known as weight

friction >

the force that results from two surfaces sliding across each other or attempting to slide across each other

applied >

a push or pull on an object from a person

tension >

a pull on an object from a rope, a wire or a cable

normal >

a supporting force by a solid surface on an object pressed against the surface, this force is always perpendicular to the surface

spring >

a force resulting from a stretched spring pulling an object as the spring goes back unstretched

air resistance >

force resulting from air molecules pushing on an object as the object moves through the air

newtons 2nd law >

• acceleration of an object is directly proportional to and in the same direction as net force on an object

• objects acceleration is inversely proportional to its mass

newtons 2nd law equation >

F = mass x acceleration

newtons 1st law >

an object at rest will remain at rest and an object in motion at a constant velocity will remain at that constant velocity until acted on by an unbalanced force

what is an unbalanced force?

a net force other than zero

what is another way to say newtons 1st law?

law of inertia

dynamics >

the study of how forces affect the motion of of objects

what is the relationship between objects mass and acceleration?

inverse relationship

what is the relationship between net force and acceleration?

direct relationship

mechanical equilibrium means that the sum or forces is zero, so what is the acceleration?

also zero

if the net force of an object is zero, what could the objects motion be described as?

the object is either at rest or in constant motion

if the net force is greater than zero, acceleration occurs. what is the change in motion caused by acceleration?

increasing speed or starting, decreasing speed or stopping, and change in direction

mass >

• not a force

• measured in kg

• does not depend on location

• scalar quantity

weight >

• is a force

• measured in N

• vector quantity

• depends on location in account to gravity

what does stationary mean?

at rest

what does mechanical mean?

refers to motion

ΣF = 0 >

means sum of

ΣF is also equal to >

F_net = ma

a =

F_net / mass

weight formula >

mass x gravity

how to get g to kg?

move to left 3

how to get cm to m?

move left 2

force >

push or a pull, an attraction or repulsion

contact forces >

a force that acts at a point of contact between two objects

what does contact forces mean?

objects have to touch each other for a contact force to exist

field forces >

a force that does not require physical contact and acts through a field

what are field forces also called? why?

long distance forces because they can act between 2 objects that are long distances from each other

field >

an abstract physical quantity

what are examples of a field force?

gravitational, electrical, magentic forces

what are contact forces?

all forces discussed in class

net force >

the vector sum of the individual forces acting on an object at any particular time

what is F_net equal to?

weight

how do you find applied force?

adding together weight and F_net