It must have a medium. It must travel in empty space. Mechanical waves are waves which needs medium of propogation.
<span>During winter for a given hemisphere, solar radiation reaches the lowest period of its annual cycle due to the tilt of the earth on its axis. As the earth rotates around the sun, this tilt occludes a portion of the energy released by the sun as it diffuses in the atmosphere.</span>
<span>force applied causes movement of an object in the same direction as the applied force.</span>