Iwant to design a laboratory experiment to determine the coefficient of static friction between an object and a surface, and prove that the coefficient of static friction is dependent only on the surfaces in contact and is not affected by any change in the mass of the object.
-what procedure should i carry out?
-what would be any safety precautions that i could take?
- what would be any limitations to the experiment ( if any)?

Imagine an isolated positive point charge q (many times larger than the charge on a single proton). there is a charged particle a (whose charge is much smaller than charge q) at a distance from the point charge q. on which of the following quantities does the magnitude of the electric field created by charge q at particle a's position depend? check all that apply. the type of the charge on the charged particle athe relative orientation between q and a (while the distance between q and a is fixed)the specific location of the charged particle a (while the distance between q and a is fixed)the amount of the charge on the point charge qthe specific location of the point charge q (while the distance between q and a is fixed)the distance between the point charge q and the charged particle athe amount of the charge on the charged particle a