What are the parts of an atom

1 electrons neutrons and protons?

2electrons and protons electrons protons neutron?

3 electrons protons neutrons and a nucleus

answer the questions above

Which of the following is an example of units for speed

In science and physics what is the standard unit of measure for speed?

Consider a double atwood machine constructed as follows: a mass 4m is suspended from a string that passes over a massless pulley on frictionless bearings. the other end of this string supports a second similar pulley, over which passes a second string supporting a mass of 3m at one end and m at the other. using two suitable generalized coordinates, set up the lagrangian and use the lagrange equations to find the acceleration of the mass 4m when the system is released. explain why the top pulley rotates even though it carries equal weights on each side.