Copper conducts electricity
Physical: Mountains, Beaches, Sea
Human: Buildings
At Z ... slowest speed
At Y ... fastest speed
At X ... medium speed
Wherever it is in its orbit, the line from the planet to the Sun smears over the same amount of area every second.
That's Kepler's second law of planetary motion.
The reason this happens is: That's how gravity works. (A better explanation is available, but first you have to be able to twirl calculus and solid geometry in the air on long sticks.)
Answer:
Ideal machines are said to have parts which are weightless , frictionless and strings if any are inextensible. Practical machines have parts which have weights, friction and it causes some loss of work done.
Explanation: