Testing and Modifications

Run number (1) (Disk Car)
Mass of mousetrap car: 103g
Mass of each wheel (or one of they are all the same): 9.1g
Wheel diameter : 12.0 cm
Axle diameter: 0.3cm
Length of string (from end of level to axle): 20.0 cm
Length of lever extension: 0.0 cm
Overall length: 26.8 cm
Overall width: 13.6 cm
Overall height: 6.2cm





Total time of test run /s: 0.0s
Total distance of test run /m: 0.0m

Observation 1 (Was the car in steady and stable motion?):
No. It did not move at all.

Observation 2 (Was the car moving in a straight line mostly?):
No. It did not move at all.

Observation 3 (Did lever and string operate smoothly as well as expected?):
No. The string was pulled, however even though the wheels moved, it stayed the same position.

State 1 area of modification :
Everything.

State rational for the above proposed modification:
1. We realised that the car did not moved because the center of gravity was at the wheels, hence when the wheels turned, it does not move because the force acting on the wheels is greater than the forward force. Hence, we wish to make the wheels lighter.
2. The chassis was not heavy, which cost the weight to be acting on the wheels only. Hence, the next design the chassis will be slighter bigger and heavier.
3. String was to thin and did not give enough pull force as expected. Hence we would like to use a thicker and rounder string so that the run will be smooth.
4. We should have added a lever string to aid in the movement. But we didn't. So now we know that the lever is an important role to play in the movement of the car.


Run number (2) (Red Car)
Mass of mousetrap car: 234g
Mass of each wheel (or one of they are all the same): 25.8 g
Wheel diameter : 6.7 cm
Axle diameter: 0.2 cm
Length of string (from end of level to axle): 17.6 cm
Length of lever extension: 15.8cm
Overall length: 28.3 cm
Overall width: 15.0 cm
Overall height: 8.1 cm




Total time of test run /s: 1.0s
Total distance of test run /m: 0.34m

Observation 1 (Was the car in steady and stable motion?):
Yes. It ran without "flying" or moving around too much.

Observation 2 (Was the car moving in a straight line mostly?):
No. It shifted to the sides a little.

Observation 3 (Did lever and string operate smoothly as well as expected?):
No. We thought that the with the extension of the lever, the movement of the car will be greater, however seems like there was a problem with the car itself.

State 1 area of modification :
The sides of the car

State rational for the above proposed modification:
1. The edges were sharp and were not user-friendly. Hence, we decided to tape it up with tapes to soften the sides so that people can touch the car without worrying about getting cut.
2. We realised that our modified car was a little light and might hold the risk of flying, hence adding a little weight may help in stabilising the car.
3. More importantly, because it moved to a certain direction, we decided to add weight to the other side to balance out the weights so that the car will move in a straight line.


Run number (3) (Blue Car w/ no weights)

Mass of mousetrap car: 257g
Mass of each wheel (or one of they are all the same): 25.8g
Wheel diameter : 6cm
Axle diameter: 0.2 cm
Length of string (from end of level to axle): 17.6 cm
Length of lever extension: 15.8cm
Overall length: 28.6 cm
Overall width: 15.0 cm
Overall height: 8.4 cm
video







Total time of test run /s: 5.15s
Total distance of test run /m: 1.21m

Observation 1 (Was the car in steady and stable motion?):
Yes. The car did not flip or leave the ground during movement.

Observation 2 (Was the car moving in a straight line mostly?):
Yes. The car travelled mostly in a straight line.

Observation 3 (Did lever and string operate smoothly as well as expected?):
Yes and no. We expected that the car will move immediately after the trap is released, however, it took awhile for it to move.

State 1 area of modification :
The weight of the chassis

State rational for the above proposed modification:
1. We realised that the center of gravity (CG) of the car was at its wheels, hence the decided to shift it to the center because there will be less load of the wheels, which will make the car move forward more.

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