Newton's Third Law Of Motion
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Lilla E. Green Hartigan Elementary School
8 West Root Street
Chicago IL 60609
This mini-teach is designed for grades 4 - 6. Pupils will verbalize and
demonstrate Newton's 3rd Law of Motion: action and reaction.
These materials will be used for teams of five - six pupils.
long party balloons
straws (milkshake size)
empty soda pop can with the opener lever intact
bucket/tub of water
11 x 14 piece of cardboard
ten foot nylon rope
wind-up Tomy truck
giant skateboard (about 20 ft.)
two demo spring scales
fan cart (Pasco dynamics cart w/ personal face fan attached)
three foot skateboard
Have four - five pupils attempt to get balloons across the room. Some may
throw them across, blow them up and release them, or walk them across the room.
Lead them to realize that they need a direction for their balloons. Now, have
pupils inflate balloons as a team and launch them in races. The balloons slide
along the strings on the thrust produced by escaping air. Then pupils discuss
what happened and try to give reasons for what they observed. Next, teams
travel through four stations which reinforce the idea of action/reaction. The
stations are described below:
(1) Soda Pop Can Hero Engine - Pupils observe water
streaming through 4-6 holes (made by a nail) in the
bottom of a suspended soda pop can. The water causes
the can to rotate in the opposite direction from the
direction of the streaming water.
(2) Three foot skateboard - Pupils line up and step up on
the skateboard, one at a time. As the pupils step off
the skateboard, they are to observe what happens.
Safety Note: Have someone hold their hand as they
step off the board.
(3) Truck and Marbles - Pupils space about 20 - 25 marbles
evenly under a 11 x 14 square cardboard. Then a Tomy
wind-up truck is placed carefully on the cardboard.
When the lever is released, the pupils are to observe
(4) Demo Spring Scales - Pupils pair off and hook one demo
spring scale to the hook of their partner's spring.
One tries to pull with a force of 4 Newtons while their
partner tries to pull at a force of 8 Newtons. Pupils
will describe the situation and tell what happens and
Groups rotate every four minutes (teacher uses the timer to keep groups on
task). At the end of the sixteen - twenty minutes, each group nominates a
reporter to share the findings of their team.
As a closing activity, pupils play "Tug Of War" using the giant 20 foot
skateboard. First, pupils pair off and join hands with their partners. A piece
of masking tape marks the starting off position. Whichever partner comes over
the tape, loses the round. Next, have a person with a small physique go against
four larger people using the nylon rope, which is looped at both ends.
Naturally, the small pupil loses. Then have the four larger pupils stand on the
giant skateboard, and have pupils predict the outcome of the tug of war. The
class discusses what happened and why. Then a general rule or law is produced
through total group participation.
Groups write up their thoughts about each station and post their group's
conclusions on the chalkboard. Selected persons report orally before the class.
Fan Cart: Attach a personal fan to a Pasco dynamics cart with tape. Turn it
on. The class concludes that the action of the blades on the fan is the cause of
the cart gliding in the opposite direction. This gliding is the reaction force.
Pupils form the general law which states that actions take place in pairs with
reactions. For every action, there is an opposite (and equal) reaction. For
example, with the Hero Engine, water streams in one direction and the can
rotates in the opposite direction. With the truck and marbles' activity, the
truck goes in one direction while the cardboard goes in the opposite direction.
As the person steps off the skateboard, they exert an action force on the board,
making it go in the opposite direction. Pupils found that they could not pull
on opposite ends of the Demo Spring Scales with different amounts forces. As
they pulled, the scales always read the same force. In every activity, pupils
conclude that whether a balloon is racing along a string, or whether one is
engaged in a tug of war, there will never be an action force exerted without a
resulting reaction force.
New Explorers: "Endeavors/Mae Jemison"
Globe's: Concepts and Challenges - Physics
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