Car on road:
pairs of action reaction:
- Car on road
- Road on car
WHAT IF
We built a "rocket" : we had a string from 1 place 2 another then we put a straw in the string and attached the balloon to the straw w/ rope... and let it go
we titled the rope so it could come back, later on...
what are the acction - reaction pairs for the rocket???
HELP
2006-11-21 10:43:49 · 3 answers · asked by BeatyIsInTheEyesOfTheBeholder 1 in Science & Mathematics ➔ Physics
the major action/reaction pair is :
the air escaping from the baloon- action.
the rocket reacting by moving forward- reaction.
everytime the rocket veers from a straight line path this is another action. the reaction is the force of the rope on the straw holding the rocket on track
2006-11-21 10:52:41 · answer #1 · answered by MrWiz 4 · 0⤊ 0⤋
Rocket Propulsion
The most important application of Action/Reaction.
Inflate a balloon. Let it go with. Observe the motion of the balloon through the air of the room.
Predict how the balloon would move in the vacuum of space.
In the early 20'th century Robert Goddard was experimenting with liquid fueled rockets.
He hypothesized that these rockets could be used to travel through the vacuum of space.
The New York Times published an article in 1920 that called his claims ridiculous since there was no air for the rocket exhaust to push against in outer space. As anyone knew, the paper explained with an editorial eye roll, space travel was impossible, since without atmosphere to push against, a rocket could not move so much as an inch. Professor Goddard, it was clear, lacked "the knowledge ladled out daily in high schools."
The Times had missed action/reaction forces.
A net force on the air accelerates it out of the balloon, A reaction force accelerates the balloon.
This is not a force isolation diagram.
The air inside the balloon is under pressure greater than atmospheric pressure due to the compression by the stretched rubber skin. When the inflator valve is opened the air in the balloon accelerates out under the action of the high pressure inside the balloon and the low pressure outside. The action force is the force of the balloon on the air, the reaction force is the force of the air on the balloon. This reaction force propels the balloon in the opposite direction from the exhaust gasses.
After the Apollo moon landing, the New York Times took a backward glance at its attack on Robert Goddard, published 49 years before. "Further investigation and experimentation," said the paper in 1969, "have confirmed the findings of Isaac Newton in the 17th century, and it is now definitely established that a rocket can function in a vacuum as well as in an atmosphere. The Times regrets the error.
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Magnet collisions
Check out the magnet collision activity an the magnetic atmosphere model activity.
Magnetic atmosphere model
A model of the atmosphere using donut magnets on a pencil.
Magnetic atmosphere model: Place two donut magnets on a pencil so that they repel. Then stack 3, 4 and 5. Notice the spacing between the magnets, they are close together at the bottom of the stack and far apart at the top. This is the same as the spacing of molecules in the atmosphere of a planet.
A force isolation diagram for a magnet suspended above another magnet on a pencil.
.Fg is the force of gravity on the top magnet, its weight, while Fm is the force from the bottom magnet.
A stack of three magnets. Fmt is the force of the top magnet on the middle magnet, Fg is the force of gravity on the middle magnet., and Fmb is the force of the bottom magnet on the middle one. The force Fmb must be larger so the magnets must be closer.
In this drawing the force of the top magnet on the middle one, Fmt, is the reaction force to the force of the middle one on the top one. The force on the top magnet by the middle magnet must support it against gravity. So the bottom magnet must exert a force on the middle magnet that is large enough to support the weight of two magnets.
Now you can figure out all the forces in the stack of 5 magnets in the photo.
Magnet Collisions
The forces on the two magnets as the top magnet falls under gravity toward the bottom one.
The forces on the two magnets in the silent collision activity in which the top magnet is dropped onto the first.
Fg is the force of gravity, Fms is the force of steel eraser on the magnet, Fmb is the force of the bottom magnet on the top, and Fmt is the force of the top on the bottom.
There is an action reaction pair of forces shown in this drawing. Which forces are they?
What is the reaction force to Fms?
Answers: The action reaction pair of forces is Fmt and Fmb .
The reaction force to Fms is the force of the magnet on the steel eraser.
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Film can rocket
A rocket can be made with a film can.
The best film cans to use are the white ones with thick tops, the worst ones are the black film cans which often leak gas.
To Do and Notice
Put water into the film can until it is 1/4 full.
Put baking powder into the depression that is inside the lid.
Fill the lid with baking powder and then put water into the film can.
Put the lid on the film can, place it on the ground and step back. After ten seconds there will be a "pop" and the film can lid will be launched into the air.
Put the lid on the can and step back.
What's Going On?
Baking powder contains a dry tartaric acid powder in addition to bicarbonate of soda. Whe wet by water the tartaric acid dissolves and reacts with the bicarbonate releasing carbon dioxide gas. The pressure builds inside the can. When the pressure is great enough the lid of the film can is blasted into the air.
Going Further
What happens if you put the lid on the floor and the film can upright?
What happens when you put the film can on its side?
Try various amounts of water, which yields the greatest height?
You can also use vinegar and baking soda, however the reaction proceeds so rapidly that you may not have time to escape before the lid blasts off.
Try warm water and cold water.
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A small car collides with a large truck head-on.
Discuss the force that the truck exerts on the car and the force that the car exerts on the truck.
Solution: these forces are an action-reaction pair.
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2006-11-21 10:54:17 · answer #2 · answered by Viri 2 · 0⤊ 0⤋
balloon on straw
straw on balloon
straw on string
string on straw
etc
2006-11-21 10:56:38 · answer #3 · answered by Jimbo 2 · 0⤊ 0⤋