Mass vs. Weight & Inertia

1. What is Gravity?
A force of attraction
between objects due to their
masses.
This attraction causes
objects to pull on other
objects.

2. How does mass & distance affect the
gravitational pull between objects?
Large mass & close in distance =
Large gravitational pull/force
Close in distance, but small mass =
Small gravitational pull/force
Large mass, but large distance = Small gravitational force

3. What is Weight?
•The amount of gravitational force
exerted on an object.
•The sponge & brick are the same size (volume), but
the brick has a much larger mass
•The Earth’s gravity will pull on the brick more =
MORE WEIGHT for the brick

4. Why do people often confuse the
terms mass & weight?
•On Earth, mass &
weight remain
constant so people
use the words as if
they mean the same
thing
*Weight DEPENDS on Mass –
They are not the same thing!

5. Mass is……….
•A measure of the
amount of matter in
an object
•Always constant
no matter where
the object is in the
universe
•Measured with a
triple beam
balance
•Expressed in
grams (g)

6. Weight is……….
•A measure of the
gravitational force
on an object
•Varies depending upon where
the object is in relation to the
Earth (or any other large body in
the universe)
•Measured with a
spring scale
•Expressed
Newtons (N)

7. FINAL SUMMARY
MASS STAYS THE SAME!
WEIGHT CAN CHANGE!

8. What is Inertia?
•The tendency of all
objects to resist any
change in motion.
•An object at rest will stay at
rest unless a force causes it
to move
•An object in motion will
stay in motion unless a
force causes it to stop.

9. How does mass affect inertia?
•More mass = more inertia
*HARDER to start or stop an
object
•Less mass = Less inertia
*Easier to start or stop an
object