##### Lecture 1 Newton's 1st and 2nd Laws

t

time

seconds [s]

M

mass

kilograms [kg]

f

force

newtons [N]

X

position

meters [m]

ΔX

change in postion

V

velocity [m/s]

a

acceleration [m/s2]

What happens when a tennis ball is released from you hand?

Gravity causes the ball to fall

Velocity increases

change in position

change in velocity

Velocity

change in position/time

Speed with direction

60 mph vs. 60 mph north

acceleration

change in velocity/time

Force

push or pull

Mass

measure of the amount of stuff

resistance to change in motion

Newton’ second Law

acceleration is proportional to force and inversely proportional to mass

a = F/M or F = MA

Net Force

sum of forces

ΣF=ma

When F = 0 then a = 0

equilibrium

static of dynamic

static equilibrium

at rest

dynamic equilibrium

moving at constant velocity

Newton’s 1st law

Law of Inertia

an object at rest will stay at rest and an object in motion will move with constant velocity unless acted upon by an external force

Friction

force that opposes motion

Inertia

tendency for an object to maintain motion

Force of Gravity

weight

“free fall”

If gravity is the only force acting on an object then the object, will free fall. Force of gravity always straight down

Drag

force upward

Terminal Velocity

When drag = weight constant speed results (ex. parachuting)

dynamic equilibrium

Weight always straight down but normal force not always straight up

Tension

pulling force exerted by a string, cable, chain, or similar solid

Aerodynamic forces

F = ma

force = mass/acceleration

[N] = [kg][m/s2]

...

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Maximum Height

ΔX = Vt when a = 0

ΔX = Vaverage t