Multiple select
which of the following discoveries are attributed to johannes kepler? select all that apply.
the orbits of the planets are ellipses.
the earth is round.
gravitational forces govern planetary motion.
all planets move in elliptical orbits with the sun at one focus.
a line connecting a planet to the sun sweeps out equal areas in equal time periods.

An electron is traveling with initial kinetic energy k in a uniform electric field. the electron comes to rest momentarily after traveling a distance d. (a) what is the magnitude of the electric field

Ascientific blank must be testable and capable of being proven false?

Asolid cylinder and a cylindrical shell have the same mass, same radius, and turn on frictionless, horizontal axles. the cylindrical shell has light-weight spokes connecting the shell to the axle. a rope is wrapped around each cylinder and tied to blocks of equal masses that are held the same height above the ground. both blocks are released simultaneously. the ropes do not slip. which block hits the ground first? or is it a tie?