Electrostatic forces are non-contact forces; they pull or push on objects without touching them
 
        
             
        
        
        
Answer:
calar quantity, length of path. displacement: vector quanity, "as the crow flies" difference between start and finish regardless of path taken. Term.
Explanation:
 
        
             
        
        
        
Answer:
Use of telemetry and radar astronomy
Explanation:
An astronomical Unit (AU) is a unit of measuring distances in outer space, which is based on the approximate distance between the earth and the Sun.
After several years of trying to approximate the distance between the Sun and the Earth using several methods based on geometry and some other calculations, advancements in technology made available the presence of special motoring equipment, which can be placed in outer space to remotely monitor and measure the position of the sun.
The use of direct radar measurements to the sun (radar astronomy) have also made the determination of the AU more accurate. 
A standard radar pulse of known speed is sent to the Sun, and the time with which it takes to return is measured,  once this is recorded, the distance between the Earth and the Sun can be calculated using 
distance = speed X time.
However, most of these means have to be corrected for parallax errors
 
        
             
        
        
        
Answer: The correct option is option E (the Sun is seen blocking different constellations in the course of a year.
Explanation: 
The earth, which is one of the planets of the solar system that supports life, is shperical in shape. The spherical ( round) shape of the earth is marked by the intervening highlands and oceans on its surface.
Evidence to show that the earth is shperical are:
--> The Lunar eclipse: During an eclipse of the Moon, the shadow of the Earth is always seen to be round.
--> Ships Visibility: When ships travel a large distance away, we see their hulls disappear first and their masts disappear last.
-->Altitude of Polaris (North Star): The height of the North Star changes as we travel to different latitudes. That is ,increases as you move toward the North pole, or decreases as you move toward the equator.
--> Aerial photographs: Photographs of the Earth from space always show a round body.
The statement that doesn't prove that the earth is spherical in shape is (the Sun is seen blocking different constellations in the course of a year). The sun is seen in front of stars blocking different constellation in a year because the earth orbits round the sun in a year and not that it is shperical in shape.