Submarines use a device called Periscope that uses the concept of multiple reflections and help us see objects above the watersurface.
<u>Explanation:</u>
When a light ray falls on a reflecting surface like a mirror, it gets reflected. In multiple reflections, the incident light ray is made to reflect multiple times by arranging the reflecting surfaces in different ways.
In submarines, we use Periscope, which is a long tube like structure. The long tube is bent at ends. It uses two simple mirrors which are placed parallel to each other at an angle of 45 degrees. The light from one mirror gets reflected to the other mirror, thus causing a multiple reflection.
When a body is thrown upwards, its velocity decreases. This is because the kinetic energy gradually changes into potential energy. At the highest point, the velocity becomes zero since the kinetic energy gets completely converted into potential energy.
