contact force
a push or pull on an object by another object that is touching it
force
a push or a pull on an object
friction
force that resists the motion of two surfaces that are touching
gravity
attractive force that exists between all objects that have mass
mass
amount of matter in an object
noncontact force
a force one object can apply to another object without touching it; e.g. the force of gravity and the electric and magnetic forces
static friction
opposes motion; prevents surfaces from sliding past each other; increases as applied force increases
sliding/kinetic friction
opposes motion between sliding surfaces; does not increase, so increasing the applied force makes objects slide faster
fluid friction
occurs between a surface and materials like water and air; can result in air resistance
weight
gravitational force exerted on an object
balanced forces
combined forces form a net force of zero
inertia
tendency of an object to resist a change in its motion
net force
combination of all the forces acting on an object
Newton’s 1st Law of Motion
an object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force; also known as the Law of Inertia
reference direction
measured from a starting point to describe an object's position
unbalanced forces
combined forces that form a net force that is not zero
centripetal force
a force in circular motion that acts perpendicular to the direction of motion toward the center of the circle
circular motion
any motion in which an object is moving along a curved path
Newton’s 2nd Law of Motion
acceleration is equal to the net force exerted on the object divided by the object's mass
velocity formula
distance/time
acceleration formula
(final velocity-initial velocity)/time
acceleration units
m/s^2
Formula for Weight
W=mg
Newton’s 2nd Law of Motion formula
F=ma or a=F/m
force pair
forces that two objects apply to each other
Law of Conservation of Momentum
total momentum of a group of objects remains the same unless outside forces act on the objects
momentum
measure of how hard it is to stop a moving object
momentum formula
p=mv
momentum units
(kg)m/s
Newton’s 3rd Law of Motion
for every action there is an equal and opposite reaction
Newton
unit of force
1N =
1 kg*m/s^2
The Universal Law of Gravitation
all objects are attracted to each other by a gravitational force; the strength of the force depends on the mass of each object and the distance between them
elastic collision
colliding objects bounce off each other