Forces

a force

A vector quantity that represents a push or a pull on an object. It is measured in Newtons (N)

mass

• measure of the quantity of matter in an object

• scalar, measured in kg

weight

• force of gravity on an object

• vector, measured in N

• always points towards the center of the earth straight down

Fg

• force of gravity

• weight of an object- ALWAYS pulls straight down

• always PULLS

Fn

• normal force

• always pushes on object perpendicular to surface of contact

Ff

• force of friction

• always prevents two surfaces from sliding

• parallel to source of contact

Ft

• force of tension

• acts through a wire/rope/cable

• always pulls in direction of the wire

Fa

• force applied

• force given in the problem

field force

• does not require contact

  • ex. gravity, magnetic, electrostatic, nuclear

contact force

• requires contact

  • ex. tension, friction, normal force, air resistance

is velocity a force

no

if there is no contact, is there a force

no

if there is a source of contact, what force is always there

normal force

newton’s 1st law name

law of inertia

what is the law of inertia

an object moves at constant velocity unless acted upon by a net force

• net force= vector sum of all forces acting on an object

acceleration is 0 if and only if ______

net force = 0

is an object with no net force at rest

no- never slows down or picks up speed

what net force does a constant velocity have

zero

what is newtons second law called

law of acceleration

what is the law of acceleration

acceleration of an object is proportional to the net force acting on it and inversely proportional to it’s mass

equation for 1st law

sigmaf= add every force together

equation for 2nd law

a=sigmaf/m

what is newtons 3rd law called

law of action reaction

what is the law of action reaction

every action (force) has an equal but opposite reaction (force)

when manipulating equations, do you mix x and y components (vertical and horizontal components)

no