Answer:
Hipparchus was an ancient Greek who classified stars based on the brightness in 129 B.C. He grouped the brightest stars and ranked them 1 (first magnitude) and dimmest stars as 6 (sixth magnitude). Thus, the smaller numbers indicated brighter stars. Now, the scale extends in negative axis as well. More the negative number, brighter is the star. For example, Sun has magnitude -26.74.
This the apparent magnitude which means the classification is based on the brightness of the star as it appears from the Earth.
FORCE-physical power or strength possessed by a living being:
He used all his force in opening the window.
MOTION-the action or process of moving or of changing place or position; movement.
Total internal reflection complete reflection of a ray of light within a medium such as water or glass from the surrounding surfaces back into the medium. The phenomenon occurs if the angle of incidence is greater than a certain limiting angle, called the critical angle.
Answer:
2,4,5 are the answers
Explanation:
sky diver suit, helicopter and feather hAVE an external force pushing or floating them
