motion and gravity Flashcards
Mass
the amount of matter in an object
kilogram
the mass of1 liter of water
Newtons first law of motion (inertia)
If no net (total) force acts on an object, its
velocity is constant
Examples of newtons first law of motion
- A hockey puck glides across the ice
at constant speed until it hits something - A rocket in space will coast along a
straight line at constant speed
speed definition
rate at which an object
changes its position
Example of speed
65 miles/hour
= 105 km/hr
= 29 m/s
Velocity definition
speed PLUS direction of travel
momentum definition
p = mass x velocity
acceleration definition
rate at
which an object
changes its velocity
Acceleration can involve:
(1) increase in speed
(2) decrease in speed,
OR
(3) change in direction.
force
a push or pull acting on an
object, causing it to accelerate (i.e.
causing a change in momentum).
examples of force
grav ity = pull
electrostatic attraction = pull
electrostatic repulsion = push
magnetic f orce = push or pul
newtons second law of motion
If net f orce ≠ 0, the acceleration of an
object is proportional to and in the
direction of the f orce
second law equation
Force = mass x acceleration
F = ma
Tells us what happens when f orces ARE present
newtons third law
For every action, there is
an equal and opposite reaction
example of third law
If A pushes (or pulls) B,
then B pushes (pulls) A,
with a f orce EQUAL in size,
exactly OPPOSITE in direction.
All f orces come in pairs
Newton’s 3rd implies
conservation of momentum:
(Changes in momentum also come in pairs
Gravity
an attractive force
between all pairs of massive objects
More details about gravity
Universal law of grav itation”:
Works ev ery where, between
any pair of massiv e objects.
Gravity is the weakest of the f our
fundamental forces of nature
The gravitational force
between two objects: equation
F = G(m1m2)/d^2
equation values meanings for gravintational force
F = gravitational force
M1 = mass of one object
M2 = mass of other object
d = distance between centers of two objects
G = “universal constant of gravitation”
Grav ity depends on
MASSES of objects
Double the mass
of one object:
Force 2x larger
Double the mass
of both objects:
Force 4x larger
Grav ity depends INVERSELY
INVERSELY
on the Square of DISTANCE
between object
Double the distance
between objects:
Force ¼ as large
Halv e the distance
between objects:
Force 4x as large
