Force f acts between two charges, q1 and q2, separated by a distance d.
if q1 is increased to twice its original value and the distance between the charges is also doubled, what is the new force acting between the charges in terms of f?
1/4 f
1/2 f
f
2f

Why do electron microscopes have higher resolving power than light microscopes?

Explain to someone who knows nothing about fossils the study of invertebrate paleontology and how it scientists understand the history of the earth. be sure your explanation contains a minimum of two complete sentences.

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.