JoeyIII,
Welcome to science buddies, and thank you for your question. Has your teacher given any feedback as to why he/she has rejected your hypothesis? I will provide my opinions, but they may not fix the reasons your teacher has for rejecting. That being said, I suggest the following:
First, the following links to the project guide on this forum and includes suggestions for constructing a hypothesis. I suggest reading the sections on Variables and Hypothesis.
https://www.sciencebuddies.org/science- ... ndex.shtml
A good hypothesis states what your independent and what you think the dependent variables are and how they will react during your experiment. It is short, but should be descriptive enough so that anyone reading it knows exactly what you changed and what you thought would happen when you did. It is often written in a statement like this: "If [I do/change
X], then [
A, B, and/or C will happen." Where
X is your independent variable and
A, B, C are dependent variables (however many you think you have). Also, it needs to be specific as to what you are testing.
Now, a good experiment should have only one independent variable, that one thing you are going to change and observe the results. You state if I add more weight AND vary the size AND placement then... This indicates at least 3 independent variables. You should pick ONE that tests exactly what you wish to explore. From what you've said, it seems like you are exploring the stability of an electric motor under different mechanical loads (perhaps like the ones on an RC car). An example, I can come up with off the top of my head is something like: "If I attach a physical load to the drive shaft of a DC electric motor and increase the off-axis distance of the weight, the motor vibration will increase as the distance increases." This has only one independent variable: off-axis distance; and one dependent variable: motor vibration. Be sure you have a way to measure both distance and vibration (you need a way to put a number to this). Also, make sure you control all the other variables, such as battery power, temperature, and very important in my example, weight (you need a way to increase the distance without changing the weight of the load, to include the arm that will hold it onto the drive shaft.