Physics Unit 2A
Issac Newton (1642-1727)
An English mathematician, physicist, astronomer, theologian, and author
force
An interaction (push or a pull) between two objects
Newton's First Law
An object at rest will remain at rest and an object in motion will remain in motion at a constant speed in a straight line unless acted upon by an unbalanced force
Newton's 2nd Law Equation
F=ma
Newton's Law of Gravitation
Fg = Gm1m2/r^2
Newton's 3rd law
For every action there is an equal and opposite reaction
force units
N (newtons)
law of inertia
Newton's first law
is force a vector?
Yes, it has magnitude and direction
What is necessary to change motion, but it will not maintain it?
a force
Spring Force (Fs)
a force from a spring (follow Hooke's Law)
Normal Force (Fn)
a perpendicular force a surface exerts on an object, surface is always going to push away from itself and perpendicular
Tension Force (Ft)
a pulling force acting along a rope, chain, wire, cable, etc
Friction (Ff)
a resistance force that occurs when two surfaces rub together
kinematics
allow us to describe how an object moves
gravitational force
an attractive force that acts between any two masses
Newton's 2nd law
an object's acceleration is directly dependent on the net force acting on the object and inversely proportional to its mass
Inertia
an object's resistance to a change in motion
Applied Force (Fa)
any push or pull directly "applied" to an object
strong nuclear forces
binds protons, neutrons, and quarks together
Mass does not
change with location
Weight does
change with location
laws
describe
forces are vectors which means
direction matters
r^2 =
distance between centers
normal force and weight
do not have to cancel each other out
contact forces are
electromagnetic force simplified
it is common for a normal force to be balancing an object's weight
ex: the upward force you feel from a chair while sitting
it is possible that normal force DOES NOT BALANCE weight
ex: the upward force you feel in an elevator
theories
explain
G =
gravitational constant (6.67 x 10^-11 Nm^2/kg^2)
4 fundamental forces
gravity, electromagnetic, strong nuclear, weak nuclear
mass
how much matter an object has (atoms, molecules, particles, etc)
mass is a measure of how much
inertia an object has
weak nuclear force
involved in radioactive decay
m1 and m2 =
mass
Do scientific theories eventually become laws?
no
fundamental forces are
non-contact forces
free body diagram
shows all the forces acting on a single object
electromagnetic force
the attractive or repulsive force between electric charges
Thrust (Fthrust)
the force that pushes in the opposite direction of expelled gas
weight
the gravitational pull of a larger object on a much smaller object
what does the amount of acceleration depend on?
the magnitude of an unbalanced force and the mass
when an unbalanced force is constantly applied,
the object will have a constant acceleration
Drag (Fd)
the resistance force an object experiences as it moves through fluid ex: water, air
gravity is
the weakest fundamental force
Because the contact forces are the result of microscopic electrical interactions,
they have certain directions
What causes an object to accelerate?
unbalanced forces
Fg =
weight
equilibrium
when an object has no unbalanced force acting on it
is it possible for a moving object to be in equilibrium?
yes but only at constant velocity
is it possible for an object at rest to be in equilibrium?
yes but only for a moment (highest height of a throw)
when you feel heavy or light it is because
your normal force is different from your weight