Transcript CATAPULTS and TREBUCHETS

CATAPULTS
and
TREBUCHETS
October 18, 2005
WHAT ARE CATAPULTS AND
TREBUCHETS?
Ancient ballistic
weapons used in siege
warfare. Many large
catapults can launch a
projectile 150 – 300
meters. That’s almost a
quarter of a mile!!!
Ancient Greek Engineering
In 399 B.C.
Dionysius the
Elder, ruler of the
Greek colony of
Syracuse in
Sicily, prepared
his city for a long
war with
Carthage by
undertaking
search and
development
program.
Dionysius of Alexandria Repeating
Catapult
Greek Crossbow
Middelaldercentret
Reconstruction of a
late 14th century
Danish environment
in Denmark.
HOW DO THEY WORK?
Some catapults
work by storing
tension either in
twisted ropes or a
fixed piece of
wood.
Trebuchets work
with a pivoting
beam and a
counterweight.
WHAT’S THE MATH?
NEWTON’S FIRST LAW OF MOTION
An object at rest tends to stay at rest and
an object in motion tends to stay in motion
with the same speed and in the same
direction unless acted upon by an
unbalanced force.
MORE MATH!
A projectile has Horizontal and Vertical
velocity and acceleration.
The projectile motion equations for average
velocity are:
x = x0 + vav · t
y = y0 + vav · t – 1/2 · g · t2
Velocity is the change is distance over time.
Acceleration is the rate of change in velocity.