1. The Astronomy Picture of the Day

2. Astronomical Motion: Inertia,
Mass, & Force
Isaac Newton (1642-1727);
mathematician, physicist, &
astronomer

3. Outline
• Inertia & Mass
• The Law of Inertia
• Forces

5. Newton’s First Law (law of inertia)
• An object will remain at rest or in
uniform motion in a straight line
unless some net external force acts
upon it.

7. Force needed
to overcome
inertia

8. Key Terms
• Force (F, Vector): a push or pull. Typical
units: the Newton (N), the pound (lb).
• Inertia: the tendency of an object at rest to
remain at rest & of a body in motion to
continue in motion in a straight line at a
constant speed.
• Mass (m, scalar): a measure of the amount
of material an object contains. A quantity
measuring a body’s inertia. Typical units:
the gram (g), kilogram (kg).

9. Key Terms
• Newton’s first law of motion (law of
inertia): a body continues in a state of rest
or in uniform motion in a straight line
unless acted upon by an external force.
• Velocity (v, vector): a physical quantity
that indicates both the speed (v, scalar) of a
body & the direction in which it is moving.
• Weight (w, vector): the gravitational force
exerted on a body by the Earth (or another
astronomical object).

10. Key Terms
• Scalar: In physics, a scalar is a simple
physical quantity that does not depend on
direction. Example: time, mass, speed.
• Vector: In physics a vector is a concept
characterized by a magnitude and a
direction. Example: velocity, acceleration,
force.

11. High school teachers conduct experiments in zero gravity
aboard NASA’s “Weightless Wonder” (or “Vomit Comet”,
August/September 2006 3
although NASA doesn’t really endorse that moniker).
g Experiments Anybody Seen my Comb?
ts then returned to their
o share what they’ve
y giving presentations
experiments and devel-
ivities for use in their
d communities.
ll Aboard the
Vomit Comet"
ya Sathyasheelappa,
rld Year of Physics
Coordinator, joined the
r s a b o a rd N A S A’s
ss Wonder. Here’s his
on of being in Zero-G:
Photo credit: Vinaya Sathyasheelappa
day began early. Our
Teacher Lori DiLisi of Beaumont High School in University Heights,
rning briefing consist-
Ohio flies through the air with the greatest of ease in the weightless
me housekeeping items,
environment aboard NASA's reduced gravity C-9 airplane.
onditions, scheduling,

12. Questions for in-class discussion