periodic motion/SHM

A spring vibrates with a frequency of 3.0 Hz when a weight of 0.50 kg is hung from it. What will its frequency be if only 0.35 kg hangs from it? *please explain this as simply and clearly as possible, thank you so much :)

charged particles

There are two charged particles that repel each other with a force F. If the charge of one of the particles is doubled and the distance between them is also doubled, then what would the force be and why?

force needed for circular motion

20. a spring scale on a rotating platform indicates that the horizontal force on a 0.452 kg mass is 1.34N when the mass is 2.37m from the axis of rotation. How long does it take for the platform to make on revolution? show all work with correct answers (think physics for dummies)

the law of universal gravitation

40. you drive an automobile of mass 2.10*10(3) kg from sea level to the top of a mountain 2.05km high? What is the automobiles' change in weight? You will need the binomial expansion given in Appendix A please show all work with correct answers (think physics for dummies when explaining)

+ - charges

If a positive charge and a negative charge held near each other are released; what happens to the forces on each particle as they move?