Forces In Motion
Intended for Grade:
Subject:
Second
Science and Math
Description:
This project introduces the basic concepts of force and
motion through a series of short classroom experiments.
Objective: The student will be able to identify various types of forces
and the resulting motion associated with the applied force.
Mississippi Frameworks addressed:
•
•
Science Framework 10b: Estimate and measure length, mass, weight,
and capacity/volume using standard units of measurement (inch, foot,
yard, centimeter, meter, ounce, pound, gram, kilogram, cup, pint, quart,
and liter).
Math Framework 2b: Estimate and measure length, weight, and
capacity using standard units of measurement (e.g., inch, foot, yard,
centimeter, meter, ounces, pounds, grams, kilograms, cups, pints,
quarts, and liters).
National Standards addressed:
•
•
•
Content Standard A: Science as Inquiry
Content Standard B: Physical Science
Math Standard: Measurement
Materials:
•
Experiment One- each group will need:
• Experiment Data Sheet One
• Projectile launcher
• Rubber band
• Tape measure
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Two small blocks of differing weight (ideally one block will
weight about twice as much as the other)
Experiment Two- each group will need:
• Experiment Data Sheet Two
• Spring scale
• Three blocks of differing weight
Experiment Three- each group will need:
• Experiment Data Sheet Three
• Boat platform
• Straws
• Card stock
• Scissors
• Tape measure
• Stapler
• Stop watch
• Small battery powered fan (optional)
Experiment Four- each group will need:
• Experiment Data Sheet Four
• Tape measure
• Various object of differing weight
• Sheet of paper
• Scale (optional)
• Stop watch
Experiment Five- each group will need:
• Experiment Data Sheet Five
• Two magnets
• Iron filings box
•
•
•
•
•
Background:
Force
A force is some type of influence that causes an object to accelerate
(change velocity or direction). Force is often thought of as a push or a pull
exerted on an object. The amount of acceleration to which an object will be
subjected is dependent on the sum of all the forces acting upon the object.
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Motion
Motion is the result of an object subjected to a force. Motion can
essentially be defined as movement. More specifically, motion is the
continuous change in the position of an object relative to a reference point.
Motion involves acceleration and velocity. Velocity is an object’s speed in a
specific direction. Velocity is recorded in terms of length/time, most
commonly in meters per second (m/s), kilometers per hour (km/h), or miles
per hour (mph). Acceleration is the rate of change of velocity, in other
words, the rate at which an object increases or decreases in speed.
Acceleration is recorded in length/time/time. Such units would be
meters/second2 (m/s2), kilometers/hour2 (km/h2), or miles/hour2 (mph2).
Types of Forces
The types of forces discussed in this lesson include gravity, frictional
force, air resistance, applied force, tensional force, buoyancy, and
magnetism. Applied forces and tensional forces are often thought of as a
push or a pull. Tensional forces stretch an object like a string, rope, or wire.
Applied forces compress objects. Examples would include sitting on a stool,
pushing a box, or closing a desk drawer.
Gravity is the force that attracts objects to the center of Earth. All
objects surrounding Earth are under the influence of Earth’s gravitational
force. This can be observed by dropping an object. The result is that it will
be attracted to the center of Earth and fall to the Earth’s surface.
Frictional force is the force created when two objects move across
each other. Friction is a resistance. Frictional force can be demonstrated
by moving a block across a smooth surface and then across a rough surface.
The rough surface will produce more frictional force than the smooth
surface and thus be harder to push.
When solid objects move through a liquid or a gas, a force called drag
is produced. Drag in a gas (specifically in air) is called air resistance. The
amount of air resistance created is dependent on the surface area and
geometry of the object. An example of air resistance is the force
experienced by a skydiver in free fall. As a skydiver jumps out of a plane,
the jumper can control her free fall speed by adjusting the orientation of
her body. When the jumper is on her stomach she falls more slowly than if
she were diving headfirst. When the jumper pulls the parachute, her falling
speed is greatly reduced due to air being trapped in the parachute which is
creating drag. This can also be demonstrated by dropping a ball and a sheet
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of paper. The paper will take longer to fall since it has more surface area in
contact with the air.
Air resistance is also used to sail a sailboat. The sails of a vessel trap
air comparably to a parachute. The wind caught in the sails pushes the
vessel across the water. This force is often thought of as wind force.
Buoyancy is an upward force on an object produced by a liquid or gas
displaced by the object. These forces make objects float. Buoyancy is
dependant upon an object’s volume and its density relative to the
surrounding liquid or gas. Buoyancy can be demonstrated by floating a boat
in water or observing the way in which a helium filled balloon rises to the
highest point of a room.
Magnetic forces can exert an attractive or repulsive force on an
object. Magnetism is produced by the movement of electrically charged
particles. This force can be demonstrated by placing a magnet near metallic
objects to see if they are attracted to or repelled by the magnet.
Procedure:
Prior to Activity:
1.
Construct enough projectile launchers (Figure 1) for each group.
An easy method of constructing the projectile launcher is
outlined in the following procedure:
a. Fasten two strips of wood to a wood plank. The wood strips
should be parallel with enough room for a third strip between
them.
b. Fasten two dowels into the wood plank near the front.
c. Fasten a dowel into the third wood strip as shown.
d. Cut a rubber band and tie the ends to the dowels in the plank.
e. Draw three lines on the plank. Label them Stage 1, Stage 2, and
Stage 3.
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Figure 1: Projectile Launcher
2.
Prepare enough boat platforms for each group. The following
procedure is used to construct the boat platform (Figure 2):
a. Cut an 8½”x11” sheet of card stock in half to make two
8½”x5 ½” sheets.
b. Bend a straw about two inches from the top.
c. Staple the two inch section of the straw in the center of
the card stock. The longer section of the straw will
serve as the mast.
d. An additional straw may be needed to diagonally brace
the mast to the card stock. The brace will need to be
stapled to the mast and the card stock.
e. The students will construct the sails according to the
instructions on the experiment data sheet.
Figure 2: Boat Platform
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Activity:
1.
Begin the lesson by asking the students if they can give a
definition of a force.
2.
Discuss how forces produce motion, and introduce the concepts
of velocity and acceleration.
3.
Ask the students to name some forces they are familiar with.
List their answers on the board. Once they have thought of as
many as they can, add any remaining forces in the background
section to the list.
4.
Give a brief introduction to the different types of forces.
Provide examples of actions and have the students identify the
force causing the action. A few examples are included in the
background section.
5.
6.
Tell the students that they will be working in small groups to
conduct experiments exploring the different types of forces.
Create groups consisting of three or four students per group.
Each group will need one experiment data sheet for the
particular experiment selected.
7.
The experiments can be demonstrated in stations if additional
helpers are available. Otherwise, select specific experiments
for the students to perform.
8.
Questions on the experiment data sheets are intended to be
answered as a class. Advanced students or groups should be
encouraged to complete these tasks on their own.
Experiment One: Applied Forces and Tensional Forces
1.
Explain to the class that during this experiment they will
demonstrate that an object changes position when a force is
applied.
2.
Have the students answer the first question on the experiment
data sheet. They will list actions that involve using applied
force and tensional force.
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3.
Ask the students what effect a stronger force will have on an
object. Tell them they will experiment to confirm or deny this
hypothesis with the projectile launcher.
4.
Explain to the class how to use the projectile launcher. [There
are two projectiles of differing weight. Hook the rubber bands
on the two posts. Place one of the projectiles in between the
two guides, pull back, and release.]
5.
6.
Clear the area in front of the launcher.
There are three lines on the launcher. The farther the rubber
band is pulled back, the more force will be exerted on the
projectile. Once the launcher is on the floor, have the students
start with the lighter projectile and eject the projectile by
pulling the rubber band to each stage. They will perform one
trial at each stage for each projectile. [Note that the rubber
bands should only be pulled back as far as the lines on the
launcher indicate. Pulling them back pas the designated lines
may pose a danger to the students.]
7.
Tell the students to measure the distance the projectile
travels. They will record their data in the experiment data
sheet and answer the questions.
8.
Repeat experiment with the heavier projectile.
Experiment Two: Frictional Force
1.
2.
Briefly review frictional forces.
3.
Tell the students they will use a spring scale to record the
amount of tensional force needed to move a block. Remind the
students that the block is moving due to tensional force but
that resistance is due to friction.
4.
5.
Explain to the students that during this experiment they will
investigate frictional forces by determining what surface will
create the greatest amount of friction.
Emphasize that the blocks must be pulled at a slow, steady rate
to get a constant force reading on the spring scale.
The students will pull three blocks of differing weight across
four different surfaces. The experiment data sheet provides
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columns to record the force needed to move the three blocks
across a tile floor, carpeted floor, desk top, and one other
surface of the student’s choice.
6.
Have the students use the gathered data to complete their
experiment data sheet.
Experiment Three: Wind Force
1.
2.
Briefly describe how moving objects have resistance due to air
and how wind can be used as a force.
Explain to the students that they will be constructing sails to
identify how air resistance is dependent upon the surface area
and shape of an object.
3.
Each group will receive a boat platform with a mast. They will
follow the instructions on the experiment data sheet to design
a sail to move their boat platform.
4.
The students will measure and cut out two sails according to
the instructions and then create a third sail of their own
design.
5.
The sails will be stapled to straws and then connected to the
ship platform by sliding the straw onto the mast of the boat
platform.
6.
Each group will measure three feet on the floor and mark this
distance with tape.
7.
The group will create wind by blowing or by a small battery
powered fan to sail their boats.
8.
9.
They will record the time needed for the boat to sail three
feet. This will be repeated for each sail. They will record this
data in the experiment data sheet.
Students will then answer the question on the experiment data
sheet.
Experiment Four: Gravitational Force and Air Resistance
1.
Briefly discuss gravity as a force, explaining to the students
that gravity is what pulls them to the surface of Earth.
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2.
Tell the students that they are going to conduct a short
experiment to determine if the weight of an object affects the
speed at which it is pulled to Earth.
3.
Each group will need an assortment of items ranging from very
light to slightly heavy. These can be any objects that are not
breakable, will not cause any damage to the floor, and will not
harm the students. Such items could include a bouncy ball,
paper clip, baseball, pencil, set of keys, or other available items
in the classroom. Items that will experience significant air
resistance should not be used.
4.
If a scale is available, have the students weight the items to
the nearest gram.
5.
The individuals within the groups will take turns dropping two
items simultaneously and determine if they hit the floor at the
same time.
6.
The students will select one item among their objects and use
that object as a comparison to the rest of the dropped objects.
For example, object one will be dropped with object two and
the students will report if they dropped to the floor at the
same time by indicating yes or no on the experiment data sheet.
Next, object one will be dropped with object three and so on.
7.
Objects will be dropped from a height of one meter. [All
objects should fall at the same speed and hit the floor at the
same time if they are dropped correctly.]
8.
Have the students report their results on the experiment data
sheet.
9.
Have the students drop the selected item and a sheet of paper
at the same time.
10.
The students should identify why the sheet of paper falls
slowly to the ground. [Air Resistance]
Experiment Five: Magnetic Force
1. Briefly introduce magnetism to the class.
2. Tell the students that they will be conducting a short
experiment to determine the effects of magnetism.
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3. Each group will need one iron filings box, two bar magnets, and
an experiment data sheet.
4. The groups will move the iron filings by moving the magnet
under the bottom of the box. The iron filings will be attracted
to the magnet through the Plexiglas.
5. The students will position the magnets as shown in the
experiment data sheet and draw the pattern of the magnetic
field shown with the orientation of the iron filings.
Evaluation:
The student’s ability to identify the various types of forces can be
evaluated by inspection of responses on the experiment data sheets. An
additional short question and answer review at the end of the lesson can also
be conducted to evaluate the student’s achievement throughout the lesson.
Extended Activities:
A supplemental lesson could be done to investigate the buoyancy forces
associated with a floating boat. This could consist of identifying items that
float and exploring their properties to further explore buoyant forces. An
additional activity could involve the students creating graphs from their
results of the individual experiments.
Sources:
Bosak, Susan.V. 2000. SCIENCE IS….2nd ed. Ontario, Canada:
Scholastic Canada Inc.
Case, Steve. September 2005. Forces and Motion. National Science
Foundation, North Mississippi GK-8 Project. Accessed 2007
April 2. < http://smartweed.olemiss.edu/nmgk8/curriculum/
middleschool/fifth/forces_and_motion/Forces%20and%20
Motion.pdf >.
Wikipedia. April 2007. Force (physics). Accessed 2007 April 2.
< http://en.wikipedia.org/wiki/Force >.
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Prepared by:
Jared Holland
NSF NMGK-8
University of Mississippi
April 2007
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NAME: _________________
Experiment Data Sheet One
Experiment One: Applied Forces and Tensional Forces
1. Make a list of actions for which you would need to use applied force
and tensional force.
Applied Force (Push)
Tensional Force (Pull)
_______________
________________
_______________
________________
2. What force makes a rubber band stretch?
3. Which projectile will travel farther, the heavier or lighter projectile?
4. Perform the experiment and record your results in the table.
Stage
Projectile Data
Projectile 1
Distance Traveled
(inches)
Projectile 2
Distance Traveled
(inches)
1
2
3
5. Which projectile traveled the farthest?
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NAME: _________________
Experiment Data Sheet Two
Experiment Two: Frictional Force
1. List examples of frictional forces.
____________________________
____________________________
2. What is making the blocks difficult to pull?
3. Do you think the block’s weight increases or decreases friction?
4. Perform the experiment and record your results in the table.
Block
Friction Data
Force Shown on Spring Scale for Each Surface
Tile
Carpet
Desk
(
)
1
2
3
5. After performing your experiment, do you think weight effects
the amount of friction?
6. Which block needs the most force to move?
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NAME: _________________
Experiment Data Sheet Three
Experiment Three: Wind Force
1. What is needed to sail a boat?
2. What forces are applied to the sail?
3. Do you think the shape of the sail matters?
4. Follow the instructions to make three sails.
a. Sail 1: cut out a 2 inch by 2 inch square out of card stock.
b. Sail 2: cut out a 5 inch by 5 inch square out of card stock.
c. Sail 3: create your own sail of any shape or size.
d. Staple each of your sails to a straw
e. Measure and tape off three feet on the floor.
f. Blow into your sail to create wind to sail your boat.
g. Record the time to sail your boat three feet in the table.
Air Resistance Data
Sail Design
Time to travel three feet
1
2
3
5. Does the size of the sail matter?
6. Which sail traveled the fastest?
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NAME: _________________
Experiment Data Sheet Four
Experiment Four: Gravitational Force
1. What force attracts objects to the center of Earth?
2. What happens when an object is dropped from the sky?
3. Does the weight of the object make it fall faster?
Gravitational Force Data
Object
Weight
(grams)
Did they fall at
the same time?
(yes or no)
Paper
4. Did all objects fall to the floor at the same time?
5. Why did the paper fall more slowly than the rest of the items?
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NAME: _________________
Experiment Data Sheet Five
Experiment Five: Magnetic Force
1. What type of force is magnetism: attractive, repulsive, or both?
2. How can we use magnetic forces?
3. Draw the iron filing pattern in the boxes.
N
N
S
N
S
N
S
S
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