A electron of kinetic energy 1.29 keV circles in a plane perpendicular to a uniform magnetic field. The orbit radius (r) is 22.6 cm. (a) Find the electron's speed
(b) Find the magnetic field magnitude
(c) Find the circling frequency
(d) Find the period of the motion.

Efficiency is an act of doing something

Global warming was a major concern some people do not care global warming is fake it is not real the percentage of it happening  is slight 

The force is push or pull

The figure is missing but we can answer anyway.the correct answer is "releasing the string". in fact, when the person is holding the bow and the arrow, the kinetic energy of the arrow is still zero (because the arrow is not moving). the moment the arrow is released, it acquires a velocity v, so its kinetic energy will become different from zero: where m is the mass of the arrow and v its velocity.  all the other options, instead, do not increase the kinetic energy of the system: -  pulling farther back on the string : this will just increase the elastic potential energy of the system-  holding the arrow higher: this will increase the gravitational potential energy of the system (which is given by u=mgh, where h is the height above the ground)-  decreasing the mass of the arrow: this will decrease the gravitational potential energy of the system (which is given by u=mgh, where m is the mass)