Do Now: Gravity is a universal,
natural force that attracts
objects to each other.
If Pluto and Mars are 4000kg,
and they are 500m apart, what
would happen to the
gravitational force if they were
closer together?
1. Their gravitational force would increase
Due to the decrease in distance between them
Gravity is the pull towards the center of an object.
Weight is a force
Weight can be calculated using the equation:
W =mg



W= Weight (N)
m= mass (kg)
g= gravitational acceleration (m/s2)
W
kg m g
N
m/s2
Calculate your Weight
Suppose your actual weight on Earth is
100 lbs.
What would your weight be on Mercury?
To find this out,
simply Multiply your weight by .4
(the ratio of gravity on Mercury compared to the gravity on Earth)
Therefore: 100(.4) = 40 lbs
Weight on other planets
Mass



Mass is a measure
of the amount of
matter in an object
Mass is NOT
related to gravity
Mass of an object
does NOT change
Weight


Gravity
Weight is a
measure of the
gravitational force
between two
objects
Weight DOES
change when the
gravitational force
changes
This
force
causes
all
masses
to
attract
to one
another
Examples:
Calculate the weight of a 5kg backpack (N) on Earth
(g=9.8N/kg)
W=mg
W=(5kg)(9.8m/s2)
W= 49 N
The same back pack weighs 8.2N on Earth’s moon. What is
the strength of gravity on the moon?
g=W/m
g=8.2N/5kg
g=1.6m/s2
Complete the practice problems
1-3 on the back side!
1a. 21.56N
1b. 8.14N
1c. 8.9 m/s2
2a. 65kg
2b. 637N
2c. 240.5N
3a. 23.1 m/s2
3b. .6 m/s2
3c. 4.9N
Exit ticket:
1.
How would your weight on the moon
compare to your weight on Earth?