Transcript Slide 1 - Denton ISD

Chapter
4-1
Notes
Galileo
• Developed and
proved the theory that
–All objects fall to the
ground at the same
rate.
-This is true for ALL
objects if air is not a
factor.
Acceleration
• A change in velocity in a given time
– Due to gravity is 9.8 m/s2
– Calculate the change in velocity by:
∆v = g · t
V=velocity g= 9.8
m/s2
t = time
Practice
• A penny is dropped for 2 sec. What is
the velocity of the penny after the 2
seconds?
• The same penny hits the ground in 4.5
seconds. What is the velocity as it hits
the ground?
One More Practice
• A marble at rest is dropped from a tall
building and hits the ground with a velocity
of 98 m/s. How long was the marble in the
air?
Air Resistance
Friction caused by air that opposes the
motion of objects through the air.
As speed increases, air resistance increases
Terminal Velocity
• When the upward force of air increases
until it equals the downward force of
gravity.
• The net force will be zero.
• (about 120 mph for humans skydiving)
• http://hypertextbook.com/facts/JianHuang.
shtml
Free Fall
• When only gravity is pulling on an object
and nothing else. Only occurs without air.
• Makes mass appear to be weightless
(space)
• Orbiting occurs when an items accelerates
forward and is in a free fall.
Projectile Motion
• Curved path of a thrown or propelled
object toward the surface of the earth.
– Includes horizontal and vertical movement.
– A projected item will hit the ground at the
same time as a dropped item
Centripetal Force
• A force that
pulls items
toward the
center,
therefore
allowing a
circular motion.