2/11 Examining the effect of rubber bands on cars.
In this lab, the students had to propel their standard cars with rubber bands. Each group manipulated rubber bands in the following ways:
* Stretch the rubber band across to the opposite axle.
* Wind the rubber band in opposite directions.
* Attach the rubber band under, the over the axle.
Some of the students’ observations are listed below:
* The more we wound the rubber band, the faster and farther it went.
* When we stretched the rubber band across to the opposite axle, we increased the potential energy. Then, when we released the rubber band, it had more kinetic energy.
* Number of times you wrap the band+ the tighter you wrap the rubber band, + resistance = speed of the car.
*By winding the rubber band backwards, it would spin the axle backwards propelling the car backwards.
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* We did some testing and we put some wooden blocks on our car. When we tested it out, it didn’t go far and it got slower. We guess that the more weight you put on the car the slower the car goes and the car will not go far.
February 15th, 2008 at 12:14 pmWe learned that even though you might wrap the rubberband around a little, the car will still go far. Also, we found that if you wrapped the rubberband around one time too much, the car would go farther than everything else.
February 15th, 2008 at 12:21 pm* When you are winding the rubberband, you do not want to wind it to much because if you do, the rubberband will break. Then again, don’t wind it to little because then your car won’t go far nor will it go fast. You will want to check your car because if you don’t, it could mess up your whole test.
February 15th, 2008 at 12:23 pmSummary:
I learned that depending on what surface you put the car on depends on how far the car moves and if it will move!
Hypothesis:
February 21st, 2008 at 12:14 pmI think that when we spin the large wheel for card #1 it will only move about 15 seconds. In card #2 when we take the wheels off it won’t move very far because the friction of the tire will help the car to move.
We did some observations on February 21, 2008 about what the importance of each piece of the car is. One of them were about what the tires are for. We had to take the tires off the wheels to see why we needed them. My team noticed that without the wheels, the car would’nt go on the carpet. We tried to do the test on the table and it didn’t go far. The tires is used to help the car go because if you don’t have the friction between the tires and the floor/table, the car will not go. -XB
February 21st, 2008 at 12:20 pmObservations:
February 21st, 2008 at 12:23 pmCard 1: I think that the job of the tan hub connecter is to help the wheels so it can turn. When we turn the wheel it only moved 1 second 43 miliseconds, the second time was 1 second and 46 miliseconds, the third time was 2 seconds 94 miliseconds, the fourth time was 1 second 45 miliseconds. When we flipped one wheel inside out it only went 66 miliseconds. I observerd that when we put the tan hub connector on the outside of the wheel it went forward 86 miliseconds.
Card 2: When we took the tires off it did not move any of the four times we did it. I guess the job of the tire is to help the car have some friction so it moves.
Card 3: When we tried it on the carpet it didn’t work, but when we did it on the tile it went about in the range of 5-7 inches.
What my group noticed when testing with rubberbands was that the more resistance that is put on the rubberband, the faster the car will go. If the rubberband offers no resistance, the car will not move. This is because when the rubberband is “twirled” around the axle, the rubberband gets tighter and tighter (AKA: resistance) and when it is released, the rubberband starts spinning, trying to get off the axle, and since it is spinning the axle, the wheels start turning and off the car goes! But if the rubberband doesn’t have any resistance, the rubberband won’t turn the axle, resulting in little, or no movement.
The more resistance that is put on the rubberband, the longer that the rubberband will try to free itself again, turning the axle for longer, therefore and airgo, propelling the car even farther. Rubberband force works best on a flat surface, because the car doesn’t have enough force to go up an incline, on a rigid surface, or over an object.
February 27th, 2008 at 12:03 pm