Forces

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```					Scientific Terms                 Common Terms and Expressions

Gravitational Force (Gravity)    Pull of Earth

Magnetic Force                   Magnetic pull; magnetic push

Electrical Force (Electricity)   Static cling; static electricity; force of
an electric current; force of lightning
Mechanical Force                 Muscular Force; hurricane force;
slapshot; punch
Frictional force (Friction)      Rubbing; abrasion; roughness; force
of resistance
Tensile Force                    Tightening

Compressive force                Crush; squash; squeeze; press;
pinch; grip
Rotational Force                 Twist; turn, wring, coil, twirl
All forces have 2 components:
• Magnitude: the quantity of force
• Direction: which way force is pushing/pulling

 Use arrows in diagrams
• Top of arrow shows direction
• Thickness shows magnitude

 Unit of measure = Newton         (N)
• Named after Sir Isaac Newton
The forces     Force applied to hold rock up.

are equal in
magnitude
and opposite
in direction.

Force of gravity
Mass  is a measure of the
amount of matter or material
in an object.

Weight  is a measure of how
strong the force of gravity is
between two objects.
 Ifyou hold a rock in your hand, Earth
pulls the rock toward its centre, and the
rock pulls Earth toward its centre.
However, the rock’s mass is so small in
comparison to the mass of Earth that
when you let go of the rock, the rock
moves much farther toward Earth than
Earth moves toward the rock. In fact, it
looks as though only the rock moves.
4sgS8
Earthexerts a force of 9.8 N for
every kilogram of an object’s mass

The   force of gravity is 9.8 N/kg

The moon’s force of gravity is
approx. 1/6 of Earth’s pull. So if you
went to the moon, your mass would
be the same but your weight would
be 1/6 what it is now.
 To  pick up
something you
must overcome
the force of
gravity that is
keeping it where
it is.
 How much force
do you need to
apply to pick up a
container of milk?
 Ifa litre of milk has a mass of about
1kg
 You would have to lift upward with 9.8
N of force to pick it up! Input force

A spring scale is a device used to
measure forces.
The object to be weighed is attached
to the end of a helical spring.
How far the spring stretches (the
tension on the spring) indicates the
weight of the object
The tension is shown on a calibrated
scale on the side.
 Groupings: Pairs
 Using a spring scale, estimate and
measure forces needed to perform
 Create the following chart:

force      Force
Liftone of the standard masses in
your hand and get a feel for how
much force is needed to hold it up.
Now, lift the mass with a spring scale
and record the force in your chart.
Repeat 2 – 3 times with different
masses.                  APPROPRIATE
Be sure to select the most
spring scale.
 Now  practice a simple task, such as lifting a
pencil case, until you get a feel for the
amount of force needed.
 Then estimate the amount of force needed
actual force needed.
 Determine the difference.
 Repeat for 5 other common items (binder,
water bottle, openning a drawer, etc.)
 You may need to use string to assist you.
One per pair:
 Completed     Chart:
Be sure to include all the elements of a good data
table