Kyle lays a mirror flat on the floor and aims a laser at the mirror. the laser beam reflects off the mirror and strikes an adjacent wall. the plane of the incident and reflected beams is perpendicular to the wall. the beam from the laser strikes the mirror at a distance a=66.9 cm from the wall. the reflected beam strikes the wall at a height b=37.3 cm above the surface of the mirror. find the angle of incidence θi at which the laser beam strikes the mirror.

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)