Goal:
•
FORCES
To identify and describe the
changes in motion caused by
forces and to distinguish between
contact and non-contact forces
Why are Sheldon and Leonard having so
much trouble? (stop at 1:39)
What are forces?
Forces act on you all the time. If
you surf, you can feel many forces
pushing and pulling you in
different ways. Gravity always
pulls you down, towards planet
Earth. This force can be balanced
by the support of the surfboard
acting upwards. Forces of the
waves push you towards the
shore, and friction from the air
and water pull you back out to
sea. Surfing requires your body to
balance all those forces acting on
you. If they’re not balanced, then
down you go!
WHAT IS A FORCE?
• A force is a push, a pull or a twist
• A force is applied when something is
pushed, pulled or twisted
• For each force, list 3 examples of when
you can see this occurring in everyday
life.
Push
Pull
Twist
Recognising Forces
When objects have forces acting on them
they may:
1.Begin to move
2.Speed up
3.Slow down or stop moving
4.Change direction in which it is moving
5.Change it’s shape
6.Remain still
Contact & Non-contact
• Most forces actually touch the object they are
moving. These are called Contact forces
• Some forces can push or pull an object
without touching it and are called Non-contact
forces
Contact Forces
• When we hit a
ball with a bat we
move it with a
force that has
actually touched
the object. This is
a Contact Force
Non-contact Forces
• BUT the motion and shape of objects can
changed without touching them with anything.
• When you drop a tennis ball it speeds up as it
falls through the air.
• This non-contact force is called ……… gravity
•
Other non-contact forces that can work
without touching are ………
magnetic forces and electrostatic forces
Balanced and unbalanced forces
QUIETLY
Follow Ms Eayrs outside to learn about balanced
and unbalanced forces.
How to draw forces.
Upward push
of the ground
Pedal force
Friction
• Arrows are drawn to
represent forces
• The arrow indicates the
direction of the force
• The length of the arrow
indicates the strength of
the force
gravity
(pulling
down)
Do your own drawing
• Copy this picture into
your work book
• Draw the forces that are
acting on this man
Does your drawing agree with mine?
The man is not
moving
sideways so
the forces are
balanced.
The man is not
moving up or
down so the
forces are
balanced.
The opposing
arrows must
be the same
size
The opposing
arrows must be
the same size
REFLECTION:
WRITE DOWN TWO THINGS YOU NOW
KNOW ABOUT FORCE AND ONE THING
YOU WOULD LIKE TO LEARN MORE
ABOUT.
WRITE AT LEAST 3 SENTENCES
Knowledge and effort ratings.