TAKS Objective 4
The student will demonstrate an
understanding of motion,
forces, and energy.
TEKS 7.6 A Science concepts
Demonstrate how unbalanced forces
cause changes in the speed or
direction of an object's motion;
For Teacher’s Eyes Only
What is a force?
A force is a push or a pull.
What are examples of forces?
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Magnetism
Electric force
Wind
Any push or pull made by an object or
matter
What do forces do?
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Cause objects to start moving
Cause objects to stop moving
Change the motion of objects
Nothing at all Balanced forces do
not cause a change in motion. They
are equal in size and opposite in
direction. Unbalanced forces cause
something to either change speed or
change direction.
Forces and Motion
• Forces occur in pairs and can be
either balanced or unbalanced.
Balanced Forces
• When forces are equal in size but opposite
in direction.
Balanced forces result in:
• A net force of “zero”.
The two forces pushing against each other
are equal and cancel each other out.
• No motion
Unbalanced Forces
• Forces that are not equal in size.
• Unbalanced forces always cause a
change in motion.
Unbalanced Forces
• Unbalanced forces can also be exerted in
the same direction.
• The forces are added together in the same
direction the force is being applied.
Example
• Two people combine to push a car off the
road.
How Forces Combine
• Forces in the same direction always
combine by addition
• Forces in opposite directions always
combine by subtraction.
• Balanced forces are always in opposite
directions.
How Forces Combine
• Unbalanced forces either make
something move or change the speed
and/or direction of something that is
moving.
• Balanced forces produce no motion
(net force “zero”).
Motion and machines
• Forces are used in machines
to produce motion and make
work easier.
What are simple machines?
• Simple machines are devices that use
only one type of motion to make work
easier.
• They are used to change the size or
direction of a force.
What are the six simple
machines?
The six simple machines are:
Lever, pulley, wheel and axle, inclined
plane, wedge, and screw
Remembering the six simple
machines?
Little Wheeler Is Sick With Pinkeye
Lever, Wheel and Axle, Inclined Plane,
Screw, Wedge, Pulley
Lever
A simple machine consisting of a bar
that pivots around a fixed point, called a
fulcrum
Three Types of Levers
First Class
Second
Class
Third Class
Inclined Plane
Inclined plane-a simple machine that is a
straight slanted surface; a ramp
Wedge
A simple machine that is a double
inclined plane; a wedge is often
used for cutting.
Screw
A simple machine that is an inclined
plane wrapped around in a spiral
around a central core.
Wheel and Axle
A simple machine consisting of two
circular objects of different sizes; the
wheel is the larger of the two circular
objects.
Pulley
A simple machine that consists of a
grooved wheel that holds a rope or
cable.
Engage
1. The teacher will walk around the room
demonstrating balanced and unbalanced forces.
Students will then discuss which forces
produced motion and why.
2. Blow on a pinwheel
Use magnet to move metal object
Arm wrestle
Explore
• Activity: Try and Force Me (Blackline Master)
• Objective 1: The learner will identify forces that
produce motion.
• Objective 2: The learner will distinguish between
balanced and unbalanced forces.
• Activity Overview: Students will observe different
kinds of forces. They will determine what the agent,
receiver, and affect of each force is.
Explain
There are many types of forces:
mechanical, electrical, magnetic,
gravitational, friction, buoyancy, ect.
A force is simply anything that
produces a push or a pull.
Elaborate
• Activity: Finding Your Balance
(BLACKLINE MASTER: Data Table –
Finding Your Balance)
• Objective: The students will attempt to
identify balanced and unbalanced forces
from the Explore: Try and Force Me.
Evaluate
Visual Assessment: The teacher will
rub a balloon with wool for 30
seconds. Then the balloon will be
placed near tiny pieces of paper (.5
cm pieces of tissue work well) laying
on a table.
Evaluate
Instruct the students to:
• Make observations.
• Explain what happened in terms of forces.
Engage
The teacher will read this entertaining
story of a real accident report to
introduce forces in simple machines.
It was published by Charles Allbright
of the Arkansas Traveler.
Explore
• Activity: Keep it Simple! (Blackline Master)
• Objective: The learner will identify the six types
of simple machines from pictures of everyday
tools.
• Activity Overview: Students will read the
descriptions of the six simple machines and place
pictures of simple machines into categories.
Exploration 2
• Activity: Name That Force! (Blackline Master)
• Objective: The learner will identify where forces
are located in using simple machines, and
where the critical force occurred to produce
motion.
• Activity Overview: Students will assemble in
groups of three or four and answer the following
questions:
• In each of the pictures, tell what forces are
involved to produce motion.
• Explain where the force in each picture is
applied to produce motion.
• Explain where the critical motion takes place in
each picture.
Explain
• Pulleys are used to make work easier. By
either changing the size or the direction of
the force. In this activity, only the direction
of the force was changed. At any point
you could suspend the mass in the air and
stop pulling down on the rope. Then the
forces would be balanced.
Elaborate
• Activity: Just Hangin’ Around (Blackline
Master)
• Objective: The learner will build a mobile
made out of balanced levers.
• The students will make a mobile out of
balanced levers.
Elaboration 2
• Activity: Pull Me Up! (Blackline Master)
• Objective: The learner will use a pulley to
demonstrate how simple machines multiply
force.
• Activity Overview: Students will use a simple
fixed pulley, and a block and tackle to compare
how pulleys multiply force.
Elaboration 3
Construct Rube Goldberg Machine
It must include an example of all six
simple machines and must
accomplish a simple task of the
students’ choice.
Evaluation
• Using the Rube Goldberg machine,
students will identify the 6 simple
machines and explain how they work to
produce force and motion.