The document discusses key concepts related to motion and forces including gravity, acceleration, mass, friction, and air resistance. It defines gravity as a force of attraction between objects and explains that acceleration is affected by factors like air resistance, which opposes the motion of objects through air. The amount of air resistance depends on characteristics of the object like its size, shape, and velocity. The document also describes how as the speed of a falling object increases, air resistance increases until it balances the downward force of gravity, causing the object to stop accelerating and reach a constant velocity called terminal velocity.

2. When an object’s distance from another
object is changing.
You must have a reference point in
order to determine if something is in
motion.

3. Force or
between
objects.
attraction
two

4. Gravity and Motion
• The gravitational
constant is 9.8 m/s².
• Objects fall to Earth
at the same
acceleration
regardless of mass.

5. Measure of the force of
attraction between an
object and Earth.
A Newton is the
used to measure
metric unit
weight.

6. Force between surfaces that
resists the movement of one
surface past another surface.

7. Friction also exists
between an object rolling
across another surface.

8. What affects acceleration?
• Air resistance is a
contributing factor to
acceleration.
• Air resistance is a fluid
friction that opposes the
motion of objects through air.
• The amount of air resistance
on an object depends on the
size, shape, and velocity of
the object.
• The more surface area an
object has, the more
susceptible it is to air
resistance.

9. Acceleration continues …
• As the speed of a falling object
increases, the air resistance
increases.
• This upward force of air resistance
increases until it reaches the
downward force of gravity.
• At this point the object stops
accelerating and continues falling at a
constant velocity called terminal
velocity.

10. Acceleration continues …
• As the speed of a falling object
increases, the air resistance
increases.
• This upward force of air resistance
increases until it reaches the
downward force of gravity.
• At this point the object stops
accelerating and continues falling at a
constant velocity called terminal
velocity.