Ardrossan Academy
Dead Earth
Subtopic – SPACE –
Gravity, MASS & weight
1
Ambition – Respect - Excellence
Lesson Title:
Gravity, Mass & Weight
Learning Intention:.
To understand how the strength of
gravity affects the weight of objects on
different planets
Activity: Gravity Research & graphing
I will be successful if I can :
Use data from the internet to calculate the weight of
objects on different places in the Solar System
2
Ambition – Respect - Excellence
MASS
• All objects are made up from
tiny particles called ATOMS
– these give them MASS
• Mass is a measure of how
much matter there is in an
object - it is measured in
kilograms (kg)
• A set of scales will give you
your mass in kilograms
GRAVITY
• Gravity produces a force which
acts between all objects in the
universe
• Any two objects with mass will
have a force that attracts them to
each other
• The strength of these gravitational
forces depends on the size of the
masses involved
WEIGHT
• Weight is the name of the
FORCE caused by the pull of
gravity acting on a mass
• Like other forces, weight is
measured in newtons (N)
• On Earth, an apple with a
mass of 0.1 kg, will have a
weight of about 1 N.
(lots of people mistake weight
for mass – be careful!)
GRAVITY, STARS & PLANETS
• Stars and planets are very large
objects, which have a huge amount
of mass.
• The Earth has a mass of 6 x 1024 kg
(that’s a 6 followed by 24 zeroes)
• The Sun’s mass is almost a million
times greater (six more zeroes on
the end!)
• Because their masses are very large
they have strong gravitational forces
GRAVITY, STARS & PLANETS
• The Sun’s gravity is so
strong it keeps the other
planets in orbit around it
• Each planet’s gravity is
different due to their
different masses
• The Earth’s gravity is
stronger than Mars, but
weaker than Jupiter
GRAVITY, MASS AND WEIGHT
• The gravitational force
acting on objects on
Earth makes them feel
heavy.
• This is what we call
WEIGHT
• The greater the mass of
an object, the greater its
weight will be
GRAVITY, MASS AND WEIGHT
• Weight is related to mass
by the strength of gravity
• This can be written as a
formula –
weight = mass x gravity
• On Earth, the strength of
gravity is 10 newtons for
each kilogram (10 N/kg)
ACTIVITY 1 – GRAVITY ON
PLANETS
PLANET
Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune
GRAVITY
STRENGTH (N/kg)
• Copy the table into your
jotter, leaving room for
another column
• Using any relevant source
(website, textbook etc) find
the strength of gravity on
each planet
(on some web sites it might
be given in other units –
m/s2)
ACTIVITY 2 – BUZZ’S WEIGHT
ON PLANETS
PLANET
Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune
GRAVITY
STRENGTH
(N/kg)
Buzz’s
Weight
(N)
• Add another column to
your table headed ‘Buzz’s
Weight (N)’
• Use the formula –
weight = mass x gravity
to calculate the weight of
a 0.5 kg Buzz Lightyear
on each planet
• Use your values to draw a
bar graph showing Buzz’s
weight on different planets