美国6年级学生的初次实验报告

Purpose
Does the angle of a ramp and the weight of a car affects how fast it goes?
Introduction
Motion is change in the location of an object. An object can not move unless a force is applied to it. Motion is measured and observed relative to a frame of reference. There isn’t an absolute reference frame, so absolute motion can’t be determined. Motion is like a person pushing a big box and then the box end up in a different place.
Kinetic energy is the extra energy given at the end of a motion; this energy helps the object move longer without help. It’s like a roller coaster going downhill and the extra energy helps it go back up without the chains helping it go back up. A ramp is a flat surface with different endpoint heights.
Ramps help objects move downward easier than going down vertically. It also helps things go up easier than the vertical wall. You would probably fall backwards if you went straight up, so to steep isn’t always good. There is a price for it though; you have to use more space for the ramp.
Weight of an object is the magnitude of force that must be applied to the object to support it in the gravitational field.
I think the steepest ramp will make the vehicle go fastest because there will be more gain more energy. I also think the heavier car will go faster.
Materials
·       Pencil
·       Stopwatch
·       4 ft. × 2 ft. board of wood
·       Nails
·       2 Hotwheel Cars with a weight difference of at least 1 oz.
·       Superglue
·       Saw
·       Hammer
·       Ruler
·       Protractor
Procedure
1.    Set ramps up as shown.
2.    Put the lighter car at the top of the steepest ramp. Once you let go of the car, you can start the timer. When the car reaches the end of the ramp, stop the timer.
3.    Record the time on a data table.
4.    Do this for three trials.
5.    Repeat steps 2-4 for the heavier car.
6.    Repeat steps 2-5 on all 4 ramps.
Results
Car Speed Lab
Ramp (º)
Car (oz.)
Trial 1 (sec)
Trial 2 (sec)
Trial 3 (sec)
10º
2.375
00:00.85
00:00.81
00:00.82
10º
1.250
00:00.78
00:00.75
00:00.71
20º
2.375
00:00.53
00:00.56
00:00.60
20º
1.250
00:00.47
00:00.47
00:00.50
30º
2.375
00:00.44
00:00.47
00:00.41
30º
1.250
00:00.31
00:00.37
00:00.34
40º
2.375
00:00.35
00:00.34
00:00.37
40º
1.250
00:00.31
00:00.28
00:00.25
Conclusion
The data that I got didn’t support my hypothesis. The lighter car went faster than the heavier car. The lighter car went faster on all three trials on all 4 ramps. The heavier car was slower than the lighter car by at least 00:00.03.
: Analysis
The lighter car went faster because there wasn’t much weight to hold it down, so it had more acceleration. The heavier car was slower because the weight held it down, so it didn’t have as much acceleration. Some errors were that the times could have been wrong because I stated the timer early or late. I also could have stopped it early or late.
I was surprised that the lighter car went faster than the heavier car. I thought the heavier the car, the faster it would go because the gravity would pull it down more than the lighter car so the lighter car wouldn’t have the extra force pulling it.
Next time, I might get a laser security system and rewire it so that it will start and stop a timer when ever something passes it. If I can’t get a laser system, then I would get a timer that is easier to start and stop. I would also make the ramps longer so that I wouldn’t have to start and stop the timer so quickly. I would make the ramps longer so that the cars would get to be tested on overall speed when a short ramp only tests on acceleration.
I would like to do more cars with different weights. I would like to do different cars with different materials like plastic or metal. I would also like to do a test where the angle of the ramp is the same but the length of it isn’t.